President Barack Obama has announced that the US now formally recognize Syria’s main opposition coalition as “the legitimate representative” of its Syrian people.
Barack Obama told ABC News that the National Coalition was now inclusive, reflective and representative enough for the US to take this “big step”.
The UK, France, Turkey and Gulf states have already given their recognition.
Russia said the US had decided to place all its bets on the coalition achieving an “armed victory”.
Activists say more than 40,000 people have died in the 18-month uprising against President Bashar al-Assad.
Reports from central Syria on Wednesday said a large number of civilians from the president’s Alawite sect had been killed in a village to the west of Hama.
The circumstances are unclear but a video posted by opposition activists purported to show a young Alawite boy describing how government forces had destroyed a building where the civilians were being held hostage by pro-government militia.
The building, in the village of Aqrab, had been under siege from the Free Syrian Army and, according to the boy, as many as 300 civilians were killed,
There has been no word so far from the Syrian government and it is impossible to verify the activists’ account.
More than half a million people have now fled the conflict in Syria to neighboring countries, according to the UN’s refugee agency.
Announcing the US decision to recognize Syria’s main opposition, Barack Obama said it had earned the right to represent the Syrian people, but issued a note of caution as well.
The National Coalition for Syrian Revolutionary and Opposition Forces was formed last month and only a small number of countries have so far recognized it as the legitimate representative of Syrians.
“Obviously, with that recognition come responsibilities,” Barack Obama said.
“To make sure that they organize themselves effectively, that they are representative of all the parties, [and] that they commit themselves to a political transition that respects women’s rights and minority rights.”
Russian Foreign Minister Sergei Lavrov, expressing surprise at the announcement, said the US had decided “to place all its best on an armed victory of the Syrian National Coalition”.
President Barack Obama’s statement came as foreign ministers from 70 countries prepared to meet in Morocco on Wednesday to discuss the situation in Syria.
The Marrakech meeting will be the first time that the Friends of Syria conference is attended by the Syrian National Coalition.
US recognition of the coalition does not mean the US will begin arming rebel groups, but officials told ABC that might be approved if it was thought to help achieve a political solution in Syria.
Barack Obama warned that the US would not support extremist elements within the opposition coalition.
“Not everybody who’s participating on the ground in fighting Assad are people who we are comfortable with,” he said.
“There are some who, I think, have adopted an extremist agenda, an anti-US agenda, and we are going to make clear to distinguish between those elements.”
One group he mentioned – the al-Nusra Front – is believed to be linked to al-Qaeda and responsible for nearly 600 violent attacks in major Syrian cities in the past year, the US state department estimates.
On Tuesday, US Secretary of State Hillary Clinton designated the group a foreign terrorist organization, freezing any assets its members may have in US jurisdictions.