The United States has said it will recognise the offices of the main opposition Syrian National Coalition (SNC) as a diplomatic foreign mission and announced plans for a $27m increase in non-lethal assistance to rebels fighting to oust President Bashar al-Assad.
The announcement came at the start of a visit to Washington on Monday by a Syrian opposition delegation led by Ahmad Jarba, president of the coalition, in his first official visit to the US since the SNC was set up in 2012.
Jarba is set to meet US Secretary of State John Kerry on Thursday.
This is an important step in the path towards a new Syria, its recognition on the international stage, and its relations with Syrian nationals in the US.
State Department deputy spokeswoman Marie Harf said Washington was announcing new measures "to empower the moderate Syrian opposition and to bolster its efforts to help" those in Syria.
The US now recognises the coalition's representative offices in Washington and New York as "foreign missions under the Foreign Missions Act."
The upgrade will facilitate banking and security services for the opposition in the US and help it reach out to Syrians living in the US, Harf said.
"This is an important step in the path toward a new Syria, its recognition on the international stage, and its relations with Syrian nationals in the US," Jarba said.
He welcomed the move as "a diplomatic blow against" the legitimacy of Assad.
Syrian government forces have made gains on the battlefield and Damascus has announced a presidential election for June 3, with Assad expected to win.
Washington has said the elections are not credible and US officials have denounced them as "phony."
The State Department suspended the operations of Syria's embassy in Washington and consulates in other US cities in March, as efforts by the United Nations to broker a peace deal failed to make progress.
Diplomatic initiatives by the US and Russia to end the civil war in Syria have failed amid worsening relations between Washington and Moscow over Ukraine. Russia is Assad's main backer in the war, which is in its fourth year.
Harf said the Obama administration was working with Congress to increase non-lethal aid to the moderate opposition by $27m, bringing total assistance to about $287m.
The non-lethal aid has included medical aid and food rations, communications equipment and vehicles.
The assistance, nevertheless, has fallen far short of rebel demands for more sophisticated anti-tank and anti-aircraft weapons to turn the tables against Assad's mostly Russian-supplied forces.