紐約時報本月被敘利亞的駐蘇網軍駭倒2次
Obama Weighs ‘Limited’ Strikes Against Syrian Forces
By THOM SHANKER, C. J. CHIVERS and MICHAEL R. GORDON
August 27, 2013
WASHINGTON
— President Obama is considering military action against Syria that is
intended to “deter and degrade” President Bashar al-Assad’s government’s
ability to launch chemical weapons, but is not aimed at ousting Mr.
Assad from power or forcing him to the negotiating table, administration
officials said Tuesday.
A wide range of officials characterized the action under consideration as “limited,” perhaps lasting no more than one or two days. The attacks, which are expected to involve scores of Tomahawk cruise missiles launched from American destroyers in the eastern Mediterranean Sea, would not be focused on chemical weapons storage sites, which would risk an environmental and humanitarian catastrophe and could open up the sites to raids by militants, officials said.
The strikes would instead be aimed at military units that have carried out chemical attacks, the headquarters overseeing the effort and the rockets and artillery that have launched the attacks, according to the options being reviewed within the administration.
An American official said that the initial target lists included fewer than 50 sites, including air bases where Syria’s Russian-made attack helicopters are deployed. The list includes command and control centers as well as a variety of conventional military targets.
Perhaps two to three missiles would be aimed at each site, a far more limited unleashing of American military power than past air campaigns over Kosovo or Libya.
Some of the targets would be “dual use” systems, like artillery that is capable of firing chemical weapons as well as conventional rounds. Taking out those artillery batteries would degrade to some extent the government’s conventional force — but would hardly cripple Mr. Assad’s sizable military infrastructure and forces unless the air campaign went on for days or even weeks.
The goal of the operation is “not about regime change,” a State Department spokeswoman, Marie Harf, said Tuesday. Seeking to reassure the public that the United States would not be drawn into a civil war in the Middle East, and perhaps to lower expectations of what the attack might accomplish, Obama administration officials acknowledged that their action would not accomplish Mr. Obama’s repeated demand that Mr. Assad step down.
Some lawmakers have warned that the operation might turn out to be a largely symbolic strike that would leave the Assad government with the capability to mount sustained attacks against civilians with artillery, rockets, aircraft and conventional arms and would do little to reduce the violence in Syria, limit the flow of refugees or encourage Mr. Assad to negotiate seriously if a Geneva peace conference is convened.
Representative Eliot L. Engel of New York, the ranking Democrat on the House Committee on Foreign Affairs, suggested in an interview that the attacks go further than what appears to be under consideration by the administration, including strikes on the Syrian Air Force, its munitions depots and military fuel supplies to “tip the battle in favor of the insurgents.”
“We should try to help the rebels and help the people fighting Assad,” Mr. Engel said.
Frederic C. Hof, a senior fellow at the Atlantic Council who previously worked on Middle East issues for the State and Defense Departments, has urged that the Obama administration consider a broader military mission: destroying or significantly degrading the ability of the Assad government to carry out intensive artillery, aircraft and rocket attacks with conventional as well as chemical warheads on the civilian population.
“Something that is significantly less than that, something that is seen as symbolic, I think would just enable Bashar al-Assad to say I have stood up to the world’s only superpower and faced it down,” he said.
The main American attack is expected to be carried out by cruise missiles from some or all of the four Arleigh Burke-class destroyers within striking range of Syria in the Mediterranean: the Mahan, the Barry, the Gravely and the Ramage.
Each ship carries about two dozen Tomahawk cruise missiles, a low-flying, highly accurate weapon that can be launched from safe distances of up to about 1,000 miles. Tomahawks were used to open the conflicts in Afghanistan in 2001, in Iraq in 2003 and in Libya in 2011. Attack submarines also carry Tomahawks and are assumed to be on station in the Mediterranean as well.
Officials said that while Syrian rocket and artillery sites were expected to be targeted, there were no current plans to use Tomahawks to crater airfields used by the government to receive weapons and military supplies from Iran, an important lifeline for the Assad government.
Weapons experts said that Tomahawk missile strikes, while politically and psychologically significant, could have a limited tactical effect. The weapons are largely fuel and guidance systems and carry relatively small high-explosive warheads. One conventional version contains about 260 pounds of explosives and another version carries about 370 pounds. Each is less than the explosive power of a single 1,000-pound air-dropped bomb.
The weapons are not often effective against mobile targets, like missile launchers, and cannot be used to attack underground bunkers. Naval officers and attack planners concede that the elevation of the missile cannot entirely be controlled and that there is a risk of civilian casualties when they fly slightly high.
Some officials have also cautioned that Iranian-backed Hezbollah militants might step up terrorism around the region in reaction to American strikes on Syria. Another risk is that Mr. Assad might respond to the attack by firing missiles at Turkey or Jordan or mounting even more intensive attacks against civilians.
Although some experts believe that the Syrian government already has its hands full trying to contain the rebels and would not relish a war with the United States, they say that the Obama administration needs to be prepared for another round of airstrikes should Mr. Assad raise the stakes.
In an indicator of the complexities within Syria’s civil war, and the difficulties faced by the Obama administration in any effort to guide the conflict’s path, jihadi fighters opposed to Mr. Assad were warning one another to take steps to avoid being hit in any impending American attacks.
On Monday night, one prominent member of the Nusra Front, a rebel group aligned with Al Qaeda and designated a terrorist organization by the United Nations and the United States, used a Facebook posting to urge fellow members to move away from their bases or positions in Syria.
“All fighters in Jabhat al-Nusra,” he wrote, using the organization’s Arabic name, “please constantly change your positions and don’t share anything online. There is a conspiracy by America and its tails to hit our positions.”
Attacking chemical weapons storage sites comes with the same difficulties and risks associated with attacking munitions depots generally, and with its own special dangers, which the American military encountered in two wars in Iraq. First among them are risks of contamination to the very Syrian civilians that any military action would officially be intended to protect.
Many veterans suspect that some of the effects of Gulf War syndrome that afflicted veterans of the Persian Gulf war of 1991 were caused by exposure to chemical weapons released in clouds by conventional airstrikes against Iraq’s chemical weapons sites in southern Iraq.
After the first gulf war, an American Army unit near Kuwait breached chemical weapons while destroying conventional munitions at Khamisiyah, creating an environmental hazard that persisted throughout the American occupation of Iraq after the invasion in 2003.
Similarly, airstrikes in 1991 on bunkers at the Muthanna chemical weapons complex near Samarra, Iraq, led to security and environmental problems that continue to the present day.
During the Clinton administration, the United States and its NATO allies carried out extensive airstrikes against Serb forces in Bosnia, which weakened them to the point that a peace settlement to end the Bosnia war was negotiated in 1995 at an American Air Force base in Dayton, Ohio.
Similarly in Kosovo in 1999, an intensive NATO air campaign that lasted 78 days led to an agreement in which Yugoslav forces withdrew from Kosovo, and the region achieved autonomy and eventually independence.
Mr. Obama’s national security aides have been studying the NATO air war in Kosovo as a possible blueprint for acting militarily in Syria without a mandate from the United Nations.
A wide range of officials characterized the action under consideration as “limited,” perhaps lasting no more than one or two days. The attacks, which are expected to involve scores of Tomahawk cruise missiles launched from American destroyers in the eastern Mediterranean Sea, would not be focused on chemical weapons storage sites, which would risk an environmental and humanitarian catastrophe and could open up the sites to raids by militants, officials said.
The strikes would instead be aimed at military units that have carried out chemical attacks, the headquarters overseeing the effort and the rockets and artillery that have launched the attacks, according to the options being reviewed within the administration.
An American official said that the initial target lists included fewer than 50 sites, including air bases where Syria’s Russian-made attack helicopters are deployed. The list includes command and control centers as well as a variety of conventional military targets.
Perhaps two to three missiles would be aimed at each site, a far more limited unleashing of American military power than past air campaigns over Kosovo or Libya.
Some of the targets would be “dual use” systems, like artillery that is capable of firing chemical weapons as well as conventional rounds. Taking out those artillery batteries would degrade to some extent the government’s conventional force — but would hardly cripple Mr. Assad’s sizable military infrastructure and forces unless the air campaign went on for days or even weeks.
The goal of the operation is “not about regime change,” a State Department spokeswoman, Marie Harf, said Tuesday. Seeking to reassure the public that the United States would not be drawn into a civil war in the Middle East, and perhaps to lower expectations of what the attack might accomplish, Obama administration officials acknowledged that their action would not accomplish Mr. Obama’s repeated demand that Mr. Assad step down.
Some lawmakers have warned that the operation might turn out to be a largely symbolic strike that would leave the Assad government with the capability to mount sustained attacks against civilians with artillery, rockets, aircraft and conventional arms and would do little to reduce the violence in Syria, limit the flow of refugees or encourage Mr. Assad to negotiate seriously if a Geneva peace conference is convened.
Representative Eliot L. Engel of New York, the ranking Democrat on the House Committee on Foreign Affairs, suggested in an interview that the attacks go further than what appears to be under consideration by the administration, including strikes on the Syrian Air Force, its munitions depots and military fuel supplies to “tip the battle in favor of the insurgents.”
“We should try to help the rebels and help the people fighting Assad,” Mr. Engel said.
Frederic C. Hof, a senior fellow at the Atlantic Council who previously worked on Middle East issues for the State and Defense Departments, has urged that the Obama administration consider a broader military mission: destroying or significantly degrading the ability of the Assad government to carry out intensive artillery, aircraft and rocket attacks with conventional as well as chemical warheads on the civilian population.
“Something that is significantly less than that, something that is seen as symbolic, I think would just enable Bashar al-Assad to say I have stood up to the world’s only superpower and faced it down,” he said.
The main American attack is expected to be carried out by cruise missiles from some or all of the four Arleigh Burke-class destroyers within striking range of Syria in the Mediterranean: the Mahan, the Barry, the Gravely and the Ramage.
Each ship carries about two dozen Tomahawk cruise missiles, a low-flying, highly accurate weapon that can be launched from safe distances of up to about 1,000 miles. Tomahawks were used to open the conflicts in Afghanistan in 2001, in Iraq in 2003 and in Libya in 2011. Attack submarines also carry Tomahawks and are assumed to be on station in the Mediterranean as well.
Officials said that while Syrian rocket and artillery sites were expected to be targeted, there were no current plans to use Tomahawks to crater airfields used by the government to receive weapons and military supplies from Iran, an important lifeline for the Assad government.
Weapons experts said that Tomahawk missile strikes, while politically and psychologically significant, could have a limited tactical effect. The weapons are largely fuel and guidance systems and carry relatively small high-explosive warheads. One conventional version contains about 260 pounds of explosives and another version carries about 370 pounds. Each is less than the explosive power of a single 1,000-pound air-dropped bomb.
The weapons are not often effective against mobile targets, like missile launchers, and cannot be used to attack underground bunkers. Naval officers and attack planners concede that the elevation of the missile cannot entirely be controlled and that there is a risk of civilian casualties when they fly slightly high.
Some officials have also cautioned that Iranian-backed Hezbollah militants might step up terrorism around the region in reaction to American strikes on Syria. Another risk is that Mr. Assad might respond to the attack by firing missiles at Turkey or Jordan or mounting even more intensive attacks against civilians.
Although some experts believe that the Syrian government already has its hands full trying to contain the rebels and would not relish a war with the United States, they say that the Obama administration needs to be prepared for another round of airstrikes should Mr. Assad raise the stakes.
In an indicator of the complexities within Syria’s civil war, and the difficulties faced by the Obama administration in any effort to guide the conflict’s path, jihadi fighters opposed to Mr. Assad were warning one another to take steps to avoid being hit in any impending American attacks.
On Monday night, one prominent member of the Nusra Front, a rebel group aligned with Al Qaeda and designated a terrorist organization by the United Nations and the United States, used a Facebook posting to urge fellow members to move away from their bases or positions in Syria.
“All fighters in Jabhat al-Nusra,” he wrote, using the organization’s Arabic name, “please constantly change your positions and don’t share anything online. There is a conspiracy by America and its tails to hit our positions.”
Attacking chemical weapons storage sites comes with the same difficulties and risks associated with attacking munitions depots generally, and with its own special dangers, which the American military encountered in two wars in Iraq. First among them are risks of contamination to the very Syrian civilians that any military action would officially be intended to protect.
Many veterans suspect that some of the effects of Gulf War syndrome that afflicted veterans of the Persian Gulf war of 1991 were caused by exposure to chemical weapons released in clouds by conventional airstrikes against Iraq’s chemical weapons sites in southern Iraq.
After the first gulf war, an American Army unit near Kuwait breached chemical weapons while destroying conventional munitions at Khamisiyah, creating an environmental hazard that persisted throughout the American occupation of Iraq after the invasion in 2003.
Similarly, airstrikes in 1991 on bunkers at the Muthanna chemical weapons complex near Samarra, Iraq, led to security and environmental problems that continue to the present day.
During the Clinton administration, the United States and its NATO allies carried out extensive airstrikes against Serb forces in Bosnia, which weakened them to the point that a peace settlement to end the Bosnia war was negotiated in 1995 at an American Air Force base in Dayton, Ohio.
Similarly in Kosovo in 1999, an intensive NATO air campaign that lasted 78 days led to an agreement in which Yugoslav forces withdrew from Kosovo, and the region achieved autonomy and eventually independence.
Mr. Obama’s national security aides have been studying the NATO air war in Kosovo as a possible blueprint for acting militarily in Syria without a mandate from the United Nations.
Strike on Syria Would Cause One on Israel, Iran Declares
By THOMAS ERDBRINK
August 27, 2013
Iranian
lawmakers and commanders issued stark warnings to the United States and
its allies on Tuesday, saying any military strike on Syria would lead
to a retaliatory attack on Israel fanned by “the flames of outrage.”
The warnings came against a backdrop of rising momentum among Western governments for a military intervention in the Syria conflict over what the United States, Britain, France and others have called undeniable evidence that President Bashar al-Assad’s forces used banned chemical weapons on civilians last week, killing hundreds. Mr. Assad has accused the insurgents who are trying to topple him of using such munitions.
Iran, which itself came under chemical weapons assault by Iraq during its eight-year war in the 1980s, has been a loyal ally of the Syrian government. Iranian hard-liners often say Syria is Iran’s first trench in a potential war with hostile Western powers. Iran has blamed Israel for the conflict in Syria, saying Israel is trying to bring down Mr. Assad.
“In case of a U.S. military strike against Syria, the flames of outrage of the region’s revolutionaries will point toward the Zionist regime,” the semiofficial Fars news agency quoted Mansur Haqiqatpur, an influential member of Parliament, as saying on Tuesday.
At the same time Iran has always taken the moral high ground on the issue of chemical weapons, actively opposing their use. If it turns out that Mr. Assad’s side deployed the weapons, it will be difficult for Iranian leaders to explain their support for the Syrian president to their people, analysts point out.
A potential military intervention by the United States in Syria also represents a test for Iran’s new president, Hassan Rouhani, who condemned the use of chemical weapons on his Twitter account on Monday, but stopped short of blaming either side in the Syrian conflict.
On Tuesday the new foreign minister of Iran, Mohammad Javad Zarif, stressed that Iran condemned the use of chemical weapons by any group. He also said Iran had pressed the Syrian government to assist the United Nations weapons inspectors who are in the country conducting an inquiry.
There is no evidence, he said, that chemical weapons were used by the Syrian government. But in remarks quoted by the official Islamic Republic News Agency. Mr. Zarif said there was some evidence that such munitions had been given to what he called Takfiri groups, referring to Syria’s insurgents. Takfiri is a disparaging term used by Muslims for extremist groups that accuse others of apostasy.
Many analysts close to Mr. Rouhani privately say that Syria is an obstacle to change inside Iran. The country’s hard-liners say any attack on Syria is in fact an act of war against Iran, and point to a support pact in which both nations have vowed to defend each other in case of a military attack by a third country.
“Naturally Iran does not want to lose Syria as a foothold in the region,” said Davoud Hermidas-Bavand, a professor of international relations at Allameh Tabatabaei University in Tehran.
“But in the long run a solution for Syria will mean that officials in Tehran can soften their stance towards the U.S.,” he said. “It means we would have a more open domestic atmosphere.”
Iran is widely seen as having close coordination with Hezbollah, the militant Shiite Lebanese organization that is an ideological ally. Both regard Israel as a common enemy, and Hezbollah is reported to have many rockets deployed in southern Lebanon capable of striking deep into Israeli territory.
Iran and Hezbollah are heavily engaged in helping Mr. Assad’s side in the Syria conflict. Iranian military advisers have been seen in Syria, and Iran provides military support and training to Hezbollah fighters, who have joined the Syrian armed forces in recent months retake rebel-held areas.
Iran’s supreme leader, Ayatollah Ali Khamenei, meeting with visiting Sultan Qaboos bin Said al Said of Oman in Tehran on Monday, predicted the Syrian conflict would escalate far beyond its borders if other regional nations continued to aid the Syrian opposition.
“Their supporters must know that this fire will finally engulf them as well,” Mr. Khamenei said, according to the Mehr news agency.
The warnings came against a backdrop of rising momentum among Western governments for a military intervention in the Syria conflict over what the United States, Britain, France and others have called undeniable evidence that President Bashar al-Assad’s forces used banned chemical weapons on civilians last week, killing hundreds. Mr. Assad has accused the insurgents who are trying to topple him of using such munitions.
Iran, which itself came under chemical weapons assault by Iraq during its eight-year war in the 1980s, has been a loyal ally of the Syrian government. Iranian hard-liners often say Syria is Iran’s first trench in a potential war with hostile Western powers. Iran has blamed Israel for the conflict in Syria, saying Israel is trying to bring down Mr. Assad.
“In case of a U.S. military strike against Syria, the flames of outrage of the region’s revolutionaries will point toward the Zionist regime,” the semiofficial Fars news agency quoted Mansur Haqiqatpur, an influential member of Parliament, as saying on Tuesday.
At the same time Iran has always taken the moral high ground on the issue of chemical weapons, actively opposing their use. If it turns out that Mr. Assad’s side deployed the weapons, it will be difficult for Iranian leaders to explain their support for the Syrian president to their people, analysts point out.
A potential military intervention by the United States in Syria also represents a test for Iran’s new president, Hassan Rouhani, who condemned the use of chemical weapons on his Twitter account on Monday, but stopped short of blaming either side in the Syrian conflict.
On Tuesday the new foreign minister of Iran, Mohammad Javad Zarif, stressed that Iran condemned the use of chemical weapons by any group. He also said Iran had pressed the Syrian government to assist the United Nations weapons inspectors who are in the country conducting an inquiry.
There is no evidence, he said, that chemical weapons were used by the Syrian government. But in remarks quoted by the official Islamic Republic News Agency. Mr. Zarif said there was some evidence that such munitions had been given to what he called Takfiri groups, referring to Syria’s insurgents. Takfiri is a disparaging term used by Muslims for extremist groups that accuse others of apostasy.
Many analysts close to Mr. Rouhani privately say that Syria is an obstacle to change inside Iran. The country’s hard-liners say any attack on Syria is in fact an act of war against Iran, and point to a support pact in which both nations have vowed to defend each other in case of a military attack by a third country.
“Naturally Iran does not want to lose Syria as a foothold in the region,” said Davoud Hermidas-Bavand, a professor of international relations at Allameh Tabatabaei University in Tehran.
“But in the long run a solution for Syria will mean that officials in Tehran can soften their stance towards the U.S.,” he said. “It means we would have a more open domestic atmosphere.”
Iran is widely seen as having close coordination with Hezbollah, the militant Shiite Lebanese organization that is an ideological ally. Both regard Israel as a common enemy, and Hezbollah is reported to have many rockets deployed in southern Lebanon capable of striking deep into Israeli territory.
Iran and Hezbollah are heavily engaged in helping Mr. Assad’s side in the Syria conflict. Iranian military advisers have been seen in Syria, and Iran provides military support and training to Hezbollah fighters, who have joined the Syrian armed forces in recent months retake rebel-held areas.
Iran’s supreme leader, Ayatollah Ali Khamenei, meeting with visiting Sultan Qaboos bin Said al Said of Oman in Tehran on Monday, predicted the Syrian conflict would escalate far beyond its borders if other regional nations continued to aid the Syrian opposition.
“Their supporters must know that this fire will finally engulf them as well,” Mr. Khamenei said, according to the Mehr news agency.
Kerry Says Chemical Arms Attack in Syria Is ‘Undeniable’
By MICHAEL R. GORDON, ALAN COWELL and RICK GLADSTONE
Secretary of State John Kerry said Monday that the Obama administration
would hold the Syrian government accountable for what he called a “moral
obscenity” that had shocked the world’s conscience.
A Sharp Shift in Tone on Syria From the White House
By SCOTT SHANE and BEN HUBBARD
An Obama aide said that there was “very little doubt” that Syrian forces had used chemical weapons and that Syria’s promise to allow United Nations inspectors access to the site was “too late to be credible.”
Air War in Kosovo Seen as Precedent in Possible Response to Syria Chemical Attack
By MARK LANDLER and MICHAEL R. GORDON
President Obama's national security aides are studying the NATO air war in Kosovo as a possible blueprint for acting without a mandate from the United Nations.
Syrian soldiers see chemical agents in rebel tunnels: state TV
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A lot riding on U.N. team now in Syria: ex-top weapons investigator
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BEIRUT | Sat Aug 24, 2013 7:44am EDT
(Reuters) - Syrian state television said troops found chemical agents in rebel tunnels in a Damascus suburb on Saturday and some soldiers were "suffocating", intensifying a dispute over blame for a reported nerve gas attack that killed hundreds this week.
The top U.N. disarmament official arrived in Damascus on Saturday to seek access for inspectors to the site of the attack and the United States was realigning naval forces in the region to give President Barack Obama the option for an armed strike on Syria.
Syrian opposition accounts that between 500 and well over 1,000 civilians were killed by gas in munitions fired by forces loyal to President Bashar al-Assad, and video footage of victims' bodies, have heightened calls in the West for a robust, U.S.-led response after 2-1/2 years of international inaction on Syria's conflict.
In a clear attempt to strengthen the government's denials of responsibility for the suspected chemical assault, Syrian state television said soldiers came across chemical agents in rebel tunnels in the suburb of Jobar and some were overcome by fumes.
"Army heroes are entering the tunnels of the terrorists and saw chemical agents," it quoted a "news source" as saying. "In some cases, soldiers are suffocating while entering Jobar. Ambulances came to rescue the people suffocating in Jobar."
An army unit was preparing to storm the insurgent-held suburb, the television added.
Syrian opposition activists accuse Assad's forces of firing nerve gas projectiles into Jobar and other rebellious suburbs before dawn on Wednesday. Later in the week, activists crossed front lines around Damascus to smuggle out tissue samples from victims of the attack.
The Syrian government says it would never resort to chemical weapons against Syrian citizens and in the past has accused rebels of doing so for battlefield advantage, an allegation Western leaders have dismissed.
Assad's government has suggested rebels may have carried out the latest attack themselves to provoke foreign intervention.
Obama has long been hesitant to intervene in Syria, wary of its position straddling faultlines of wider sectarian conflict in the Middle East, and he reiterated such reluctance on Friday.
INTELLIGENCE EVIDENCE
But, in a development that could raise pressure on Obama to act, American and European security sources said U.S. and allied intelligence agencies had made a preliminary assessment that chemical weapons were used by pro-Assad forces this week.
Major world powers - including Russia, Assad's main ally which has long blocked U.N.-sponsored intervention against him - have urged the Syrian leader to cooperate with a U.N. inspection team that arrived on Sunday to pursue earlier allegations of chemical weapons assaults in the civil war.
U.N. High Representative for Disarmament Affairs Angela Kane arrived to Damascus on Saturday to press for a Syrian government green light for inspectors to examine areas of Damascus suburbs said to have been targeted on Wednesday.
Assad's government has not said whether it will give such access despite increasing pressure from the United Nations, Western and Gulf Arab countries and Russia. If confirmed, it would be the world's deadliest chemical attack in decades.
Washington said on Friday it was repositioning warships in the Mediterranean, although officials cautioned that Obama had made no decision on any military move. A U.S. defense official, speaking on condition of anonymity, said the navy would expand its presence there to four destroyers from three.
Secretary of Defense Chuck Hagel, en route to Asia, said Obama had asked the Pentagon for options on Syria.
"The Defense Department has responsibility to provide the president with options for all contingencies," Hagel said. "And that requires positioning our forces, positioning our assets, to be able to carry out different options - whatever options the president might choose." He did not elaborate.
The defense official said the USS Mahan, a destroyer armed with cruise missiles, had finished its deployment and was due to head back to its home base in Norfolk, Virginia. But, he said, the commander of the U.S. Sixth Fleet has decided to keep the ship in the region.
U.S. MILITARY OPTIONS
Among the military options under consideration are targeted missile strikes on Syrian units believed responsible for chemical attacks or on Assad's air force and ballistic missile sites, U.S. officials said. Such strikes could be launched from U.S. ships or combat aircraft capable of firing missiles from outside Syrian airspace, thereby avoiding Syrian air defenses.
But the defense official stressed the Navy had received no orders to prepare for any military operations regarding Syria.
Obama's senior national security advisers will convene at the White House this weekend to discuss U.S. options, including possible military action, against the Syrian government, another U.S. official said.
A senior State Department official said no final decisions were expected from the meeting pending a further review of intelligence on the suspected chemical attack.
The security sources said the assessment was preliminary and, at this stage, they were still seeking conclusive proof, which could take days, weeks or even longer to gather.
Obama called the incident a "big event of grave concern" and one that demanded U.S. attention, but said he was in no rush to get war-weary Americans "mired" in another Middle East conflict.
Asked about his comment - made a year and a day before the toxic fumes hit sleeping residents of rebel-held Damascus suburbs - that chemical weapons would be a "red line" for the United States, Obama was circumspect.
"If the U.S. goes in and attacks another country without a U.N. mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it," he said. "The notion that the U.S. can somehow solve what is a sectarian complex problem inside of Syria sometimes is overstated."
While the West accused Assad of a cover-up by preventing the U.N. team from heading out to Damascus suburbs, Russia said the rebels were impeding an investigation.
Obama's caution contrasted with calls for action from NATO allies, including France, Britain and Turkey, where leaders saw little doubt Assad's forces had staged pre-dawn missile strikes.
But more than two years into a civil war that has divided the Middle East along sectarian lines, a split between Western governments and Russia again illustrated the international deadlock that has thwarted outside efforts to halt the killing.
