Syria on Thursday welcomed a US-Russian initiative to find a political solution to its conflict, counting on ally Moscow to stand firm, even as Washington said President Bashar al-Assad would have to step down.
US Secretary John Kerry, who announced the initiative earlier this week, said the embattled president would have to step down as part of the resolution to the conflict.
"Syria welcomes the US-Russian rapprochement," the Syrian foreign ministry said in a statement.
"It is confident that the Russian position, which is based on the principles of the UN Charter and international law, will not change," it said.
"Only the Syrian people will decide on their future and the constitutional system of their country, with no foreign interference," the ministry added.
Russia is a top ally of the regime in Damascus and has staunchly resisted any bid to out Assad from power.
Washington, by contrast, has backed the uprising, with Kerry saying Thursday that all sides were working to "effect a transition government by mutual consent of both sides, which clearly means that in our judgement President Assad will not be a component of that transitional government."
The comments were significantly more direct than those he made in Moscow on Tuesday in announcing the initiative, which would build on a deal agreed in Geneva last year that made no mention of Assad's future.
Then, while saying it was "impossible for me as an individual" to imagine Assad continuing to govern, Kerry only the Syrian people could decide.
In Rome, Kerry also officially unveiled $100 million (76 million euros) in additional US humanitarian aid for Syrian refugees, almost half of which will go to help Jordan cope with a tide of people fleeing the 26-month war.
Washington has now pledged some $510 million dollars in humanitarian aid to the Syrian people, and a further $250 million in non-lethal aid to the rebels fighting to oust Assad.
On Tuesday, Kerry and his Russian counterpart Sergei Lavrov said they would seek to convene an international conference to build on a six-point accord agreed in Geneva last year.
The agreement aimed at finding a path towards a transitional government but made no mention of Assad's departure, which the opposition says is non-negotiable.
In its response to the initiative, the opposition National Coalition reiterated on Wednesday that any political settlement must start with Assad's ouster.
Syrian pro-regime daily Al-Watan on Thursday quoted an official as welcoming the effort and saying Russia's stance would be adopted internationally.
"All the capitals of the world will sooner or later come around to Russia's position because this position is based on international law and the right of people to decide their fate without foreign intervention."
The differences between the United States and Russia were underlined Thursday by reports that Israel has warned Washington of Moscow's plans to sell Syria sophisticated missile systems.
The Wall Street Journal reported that Israel had informed Washington about the imminent sale of Russian S-300 missile batteries, advanced ground-to-air weapons that can take out aircraft or guided missiles.
Moscow remains one of the Syrian regime's closest allies, and has continued to supply Damascus with weapons throughout the conflict, which has left more than 70,000 people dead since March 2011.
The regime has also relied increasingly on its alliance with Lebanese Shiite group Hezbollah, with a newspaper on Thursday quoting Assad as saying Syria would "give Hezbollah everything" for their loyalty.
The newspaper also quoted Assad as saying his country would follow the militant organisation's model of "resistance" against Israel, after the Jewish state twice carried out strikes against Syrian military targets last week.
Hezbollah, whose leader Hassan Nasrallah is scheduled to deliver a televised address on Thursday, is battling alongside regime troops in several parts of the country, including Qusayr in central Syria.
The military and the Syrian Observatory for Human Rights watchdog both reported on Thursday that forces loyal to Assad had advanced in the Qusayr area, which is strategically located along the Lebanese border.
"Backed by pro-regime militia and Hezbollah fighters, the army is advancing in the Qusayr area," Observatory director Rami Abdel Rahman told AFP.
"They have superior firepower and their campaign to take back Qusayr is fierce," he added.
Weeks after radical Sunni sheikhs in Lebanon called on men from the country to join Syrian rebels, two Lebanese fighters from the northern city of Tripoli were killed in Qusayr, a Lebanese security source said.