Syrian officials said Wednesday that they would stop fighting by dawn on Thursday in order to honor a cease-fire brokered by special envoy Kofi Annan, but reserved the right to respond to any aggression.
The statement came as Annan was met with officials in Tehran to seek support for his faltering plan to halt 13-months of violence in a country now on the brink of civil war.
Iran is one of Syria's most powerful allies, but Damascus' announcement is widely seen as a significant hedge against any end in the fighting that has claimed over 9,100 civilian lives.
Syrian leaders on Tuesday had previously upped the ante by demanding written guarantees the rebels would lay down their arms.
The opposition Syrian National Council agreed to provide written guarantees to end the violence, but the rebel Free Syria Army said it would only negotiate with international mediators.
Following the rebels refusal, Annan rejected the demands saying there would be "no preconditions."
Many world leaders see Annan's six-point plan, which called for Syria to withdraw its troops from population centers on Tuesday ahead of a full cease-fire by both sides by 6am Thursday, as the best hope to end the violence.
But many remain unconvinced Syrian President Bashar al-Assad's regime will fully comply after several previous examples of backsliding on agreements.
Of particular note, Assad's forces disregarded the Tuesday deadline and were still attacking its opponents with tank, rocket, and mortar fire.
There were also reports of Syrian troops rounding up and shooting dissidents, summarily executing wounded rebel fighters, and fire-bombing anti-regime activists homes across the country.
In a statement carried on the state-run SANA news agency, a defense official said Syria's army successfully fought off "armed terrorist groups," which is the term Damascus uses to describe citizens calling for an end to Assad's 11-year autocratic rule.
"A decision has been taken to stop these missions as of the morning of Thursday, April 12, 2012," the official said, adding: "Our armed forces are ready to repulse any aggression carried out by the armed terrorist groups against civilians or troops."
Annan spokesman Ahmad Fawzi said Syrian Foreign Minister Walid Moallem sent a letter with an identical pledge to the joint UN-Arab League envoy.
Fawzi said Annan "will work with the Syrian government on implementation of his six-point plan to end the bloodshed."
In neighbouring Jordan, an interior ministry official said the country was now hosting 95,000 Syrian refugees who had fled the conflict. Some 30,000 Syrian refugees are belived to have crossed into Turkey, as well.