"We have reached a provisional agreement in principle on the terms of a cessation of hostilities that could begin in the coming days," Kerry said Sunday, during a press conference with Jordanian Foreign Minister Nasser Judeh in the Jordanian capital city of Amman.
The top US diplomat, who was visiting Jordan to discuss with Judeh and King Abdullah the situation in the region, said the agreement was reached after repeated negotiations with Lavrov, that ran through early Sunday, according to Reuters.
Kerry also said that US President Barack Obama and Russian President Vladimir Putin would be speaking in the next few days to complete the agreement in principle.
He declined to reveal any details, but according to the Russian Foreign Ministry, the ceasefire conditions exclude military operations against organizations "recognized as terrorist by the UN Security Council."
According to Kerry, any deal would take a few days, while the two sides consulted with other countries and the Syrian opposition.
Russia has to speak to the Syrian government and Iran, and the US has to speak to the Syrian opposition and its partners, Kerry said.
After days of negotiation, diplomats from the International Syria Support Group (ISSG), a group of countries including the US, Russia, Turkey, Saudi Arabia and Iran, agreed on February 12 to seek a temporary "cessation of hostilities" in Syria. The ISSG also agreed to "accelerate and expand" deliveries of humanitarian aid to various besieged Syrian towns.
Syrian President Bashar al-Assad said Saturday that he was ready for a ceasefire to end the years-long bloodshed in the country, on condition that foreign-backed terrorists did not use a let-up in fighting to their advantage and that countries backing them halted their support.
Syria accuses Saudi Arabia, Turkey and Qatar of funding and arming terrorist groups operating inside the country, including Daesh (ISIL).
The Syrian opposition had earlier agreed to the "possibility" of a temporary truce, provided there were guarantees Damascus's allies including Russia would stop there airstrikes, sieges were lifted and aid deliveries were allowed country-wide.
Russia has been conducting airstrikes on the positions of Daesh and other militant groups in Syria since September 30, 2015, upon a request by the Assad government.
The US and some of its allies have also been pounding alleged Daesh positions in the Arab country since 2014, without getting approval from the Syrian government or the UN.
The foreign-sponsored conflict in Syria, which flared up in March 2011, has claimed the lives of some 470,000 people and left 1.9 million injured, according to the Syrian Center for Policy Research, Press TV reported.
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