Mattis blamed Russian Federation for Syria's chemical weapons stockpile, which Moscow said it would help eliminate as part of an agreement in 2013, but which the United States and worldwide observers said Syria used on civilians a year ago.
Mattis said that he was aware of reports of chlorine attacks on Eastern Ghouta but said that he did not have conclusive evidence that gas had been used.
The workshop was discovered in a recently-liberated area in Eastern Ghouta where Syrian troops are fighting foreign-backed extremists and Takfiri terrorists, Russian news agencies reported Monday, citing a field commander.
Syrian jets struck rebel-held towns in the country's south on Monday, the first aerial attacks on the area since the United States and Russian Federation brokered a deal making it a "de-escalation zone" a year ago, rebels and residents said. Turkish troops have destroyed water and power stations that supply the town of Afrin, making it hard for people to stay there, Ebrahim said.
The state-run TV broadcast footage showing a small group of men, women and children it says left the town of Madyara on Monday.
Ebrahim blamed Russian Federation and Turkey for what he called "war crimes that are being committed in Afrin".
"In the southern East Ghouta pocket area, the Syrian Army has, following the very recent seizure of Aftris, ceased operations for the time being to allow for the safe withdrawal of civilians and surrendering insurgent fighters into the custody of government forces".
Turkey launched a solo military offensive against the Syrian Kurdish militia known as YPG to clear them from the enclave of Afrin.
The government onslaught of Eastern Ghouta began on February 18 with a ferocious air campaign followed by a ground operation that has recaptured almost 60 percent of rebel territory.
The advances also cut off key towns of Douma and Harasta from the rest of the enclave, further squeezing the residents inside them.
Syrian government forces split eastern Ghouta in two amid rapid weekend advances, dealing a major setback to the rebels and threatening to exacerbate an already dire humanitarian situation at the doorstep of the country's capital.
The area is home to around 400,000 people living under a crippling government siege since 2013 and struggling to access food, medicine, and other basic necessities.