President Barack Obama has said the United States is considering "all options" in response to the apparent use of chemical weapons inside Syria.
He said the White House's assessment on how much aid would be provided to Syrian opposition forces was also ongoing.
"We are continually evaluating the situation on the ground, working with our international partners to find the best way to move a political transition," Mr Obama said at a press conference during a visit to Mexico.
"As we've seen evidence of further bloodshed, potential use of chemical weapons inside of Syria, what I've said is that we're going to look at all options," he added.
The US administration is considering arming rebels fighting the Syrian government, Defence Secretary Chuck Hagel said today.
Speaking at a Pentagon news conference, Hagel said that the administration was considering a range of options adding that he had not personally decided whether it would be wise to provide weapons.
The United States is rethinking its opposition to arming the Syrian rebels, US Defence Secretary Chuck Hagel has said.
Hagel stressed that no decision by US President Barack Obama had been made and did not signal whether one was likely soon.
US military commanders have voiced concerns that weapons could fall into the hands anti-American Islamic extremists and that arming opposition groups may do little to end the conflict.
"You look at and rethink all options. It doesn't mean you do or you will" choose them, Hagel said.
"These are options that must be considered with partners, with the international community: what is possible, what can help accomplish (our) objectives," he added.
British defence secretary Philip Hammond, who is in Washington for talks, noted that the UK was constrained by a European Union ban on supplying armaments to the rebels.
He said: "Both of our nations will only do what we legally can do," Hammond said, adding his government would "look at the situation when that ban expires in a few weeks' time."
US Defence Secretary Chuck Hagel says Syria is a "fluid situation... we're rethinking options... yes, of course we are". Defence Secretary Philip Hammond at the Pentagon says, "We believe the Assad regime retains control of its chemical weapons".