President Barack Obama on Wednesday backed the new Syrian opposition coalition but showed no sign he was ready to arm the rebels, warning of the dangers of pouring weapons into the volatile conflict.
"We're not yet prepared to recognize them as some sort of government in exile, but we do think that it is a broad-based representative group," Obama told reporters at his first news conference since his re-election.
But he cautioned against the growing clamor for nations to supply weapons to the rebels, fighting since March 2011 to oust Syrian President Bashar al-Assad.
"One of the things we have to be on guard about, particularly when we start talking about arming opposition figures, is that we're not indirectly putting arms in the hands of folks who would do Americans harm or do Israelis harm or otherwise engage in actions that are detrimental to our national security."
He also warned against "extremist elements" which he said had been trying "to insinuate themselves into the opposition."
Frustrated by months of in-fighting among the opposition, Washington had pushed for the formation of the Syrian National Coalition, which emerged on Sunday from marathon talks in Doha.
The leader of the new body, Ahmed Moaz al-Khatib, swiftly urged the world to arm the rebels with "specialized weapons" to "cut short the suffering of the Syrians" in the 20-month war which has killed some 37,000 people.
But Secretary of State Hillary Clinton, who also welcomed the coalition saying it would make the opposition "a more effective, representative body," also stressed that more needs to be done.
As the opposition "demonstrates its effectiveness in advancing the cause of a unified, democratic, pluralistic Syria, we will be prepared to work with them to deliver assistance to the Syrian people," Clinton told a press conference in Australia.
The United States Wednesday unveiled another $30 million in humanitarian help for the Syrian people, bringing its total aid to almost $200 million.
And it has been providing non-lethal aid, such as equipment to allow rebel groups to overcome the regime's jamming of communications networks.
France, the first country to greet the body as the "sole" representative of the Syrian people, has said countries must now review the arms issue.
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Obama first called on Assad to step aside in August 2011, and the United States has slapped sanctions on the regime and sought in vain to win similar UN moves -- thwarted by vetoes by Russia and China.
On Wednesday, Obama gave no sign though that despite his re-election there would be any major shift yet in his Syria policy.
"The US has been virtually missing in action on Syria so far, but their recent moves, including the push for the formation of the coalition, indicates that they might be ready to adopt a more proactive attitude," said pro-democracy Syrian activist, Ammar Abdulhamid, a fellow at the Foundation for the Defense of Democracies.
"The heavy lifting, though, including arming rebels and perhaps pushing for a de facto no-fly zone, might still be left to other countries at this stage," he told AFP.
US analysts said questions remained over the new coalition, highlighting for example that a Kurdish body had still not joined.
The opposition now needs to work on setting up a transitional government and some form of military council, they said.
"What the United States is looking for... is one military organization where all military aid can be channeled, that in turn can be relied upon to distribute the money among fighting groups inside the country, leaving out the jihadi groups," said Marina Ottaway, senior associate with the Carnegie Endowment for International Peace.
"This is a very admirable plan. I'm not sure that it can work," she told AFP, adding: "The idea that somehow by centralizing the distribution of money the jihadi groups will be cut off, I don't think it's realistic."
Abdulhamid agreed that before the international community could start arming the rebels a "mechanism for vetting groups and delivery channels need to be agreed."
Even calls for a no-fly zone in Syria, similar to the NATO-led one set up in Libya, would prove problematic, being costly to set up and patrol, and carrying a high risk of casualties.
One game-changer could be if the US gives a nod to its allies in the region to supply weapons, such as Stinger shoulder-launched missiles, to the rebels.
"I think it's very unlikely that the US will provide the Stingers itself. Would it give an order to countries that bought Stingers from the United States to pass them along? That we don't know, but I think that if there is a change in US policy it's likely to be in that direction," Ottaway said.