In 2013, after mounting global pressure following a chemical attack in the Damascus suburb of Eastern Ghouta, Assad government's surrendered what it claimed were all the chemical weapons it possessed.
Nine people are said to have been killed in Mhradah.
The presidents of Turkey, Iran and Russian Federation on Friday failed to agree on a ceasefire that would forestall a Syrian government offensive in rebel-held Idlib province which the United Nations fears could cause a humanitarian catastrophe involving tens of thousands of civilians.
U.S. Ambassador to the UN Nikki Haley sent another strong warning to Bashar al Assad's Syrian regime at the United Nations Friday.
"The Trump Administration and the worldwide community have made it clear that there is no military solution to the Syrian conflict", Haley told the Council, which was to hold another meeting Friday on the crisis in Idlib.
A handout picture taken and released on September 7, 2018 by the Turkish Presidential Press service shows Turkish President Recep Tayyip Erdogan (R), Iranian President Hassan Rouhani (C) and Russian President Vladimir Putin (L) joining hands during a trilateral summit in Tehran.
Trump will chair a U.N. Security Council meeting on Iran during an annual gathering of world leaders in NY later this month.
The new sanctions will target four individuals and five entities tied to the Assad regime that are believed to be conducting weapons shipments and financial transactions supporting upcoming attacks against civilians.
"But we are in a dialogue, a routine dialogue, with the president to make sure he knows where we are with regard to planning in the event that chemical weapons are used", he told a small group of reporters during a trip to India.
"The battle for Idlib is going to be the final major battle", said Hilal Khashan, a political science professor atthe American University of Beirut, told Reuters before the summit.
It is the last major rebel-held area in Syria and government forces, backed by Russian Federation, are poised to attack.
The White House said this week that U.S. President Donald Trump had warned that such attacks would be "a reckless escalation of an already tragic conflict" and "risk the lives of hundreds of thousands of people".
An official in the town of Morek, which serves as a crossing between Hama and Idlib, appealed for Turkey to intervene as it has troops and 12 observations points circling Idlib. He spoke during a summit with the leaders of Russian Federation and Iran in Tehran.
While Putin called for the "total annihilation of terrorists in Syria", he left open the possibility of a cease-fire. Crucially, the plan would also guarantee the security of the Russian air base of Hmeimeem.
"Turkey's calls on the U.S.to stop this shady relationship have fallen on deaf ears".
"We have absolutely advised them to stay out of At Tanf", one USA official told CNN.
Reacting to Erdogan's proposal for a cease-fire in Idlib, Putin said "a cease-fire would be good" but indicated that Moscow does not think it will hold. The Turks are trying to find a way out.
Jeffrey said the U.S.is taking a tougher stance and will not tolerate an all-out attack on the region.
Jeffrey warned of the risks of an offensive on the province and said the US wouldn't "tolerate an attack (on Idlib), period!"
A Syrian man receives treatment at a small hospital in the town of Maaret al-Noman following a suspected toxic gas attack in Khan Sheikhun, a nearby rebel-held town in Syria's northwestern Idlib province, on 4 April 2017. In practice it has eased the regime's bloody comeback in rebel-held territories such as Daraa and Ghouta, and now imminently in the last militant stronghold, Idlib, where the al-Qaeda-linked Hayat Tahrir al-Sham (HTS), formerly known as Jabhat al-Nusra, dominates.