Pentagon chief Chuck Hagel says the United States was positioning naval forces and assets in case President Barack Obama decides to order a military strike against Syria.
"The Defense Department has responsibility to provide the president with options for all contingencies," Hagel told reporters aboard his plane en route to Malaysia on Friday.
"And that requires positioning our forces, positioning our assets, to be able to carry out different options - whatever options the president might choose," he added.
His remarks come after some American defense officials said earlier on Friday that Washington was considering military options against Syria over the allegations of the chemical weapons use by the Syrian government.
An unnamed defense official said the USS Mahan is set to stay in the region after it had finished its deployment and was due to head back to its home base in Norfolk, Virginia.
When asked if it was fair to report that the US had moved assets, Hagel said, "I don't think I said that. I said that we're always having to prepare - as we give the president options - prepare our assets and where they are and the capability of those assets to carry out the contingencies we give the president."
On Wednesday, Syria's US-backed opposition claimed that around 1,300 people were killed in a government chemical attack on militant strongholds but some others said 100 people were killed in the pre-dawn strike. The Syrian government, however, denied the allegations.
A team sent by the United Nations is set to investigate the latest claim of chemical weapons use outside Damascus.
UN Secretary General Ban Ki-moon on Thursday asked Syria to allow UN inspectors to investigate "without delay" the alleged chemical attack.
Meanwhile, President Barack Obama said the United States cannot attack Syria without a UN mandate for the allegations.
"If the US goes in and attacks another country without a UN mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it. Do we have the coalition to make it work? And, you know, those are considerations that we have to take into account," he said in an interview with CNN on Friday.
The war in Syria started in March 2011, when pro-reform protests turned into a massive insurgency following the intervention of Western and regional states.
More than 100,000 people have died in the foreign-hatched insurgency and millions have been displaced.
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