"The cessation of hostilities is an important step forward, imperfect though it is, and it does enable the possibility of political negotiations starting next week," Cameron said during a regular Question Time session at the UK Parliament.
Asked what the UK government was doing to make sure the truce was properly enforced, Cameron said that, "We are working with the Americans and the Russians to make that happen. I’ve got a European conference call with Vladimir Putin later this week to reinforce these points."
Russia and the United States reached an agreement on a ceasefire in Syria on February 22. The accord took effect on Saturday, generally holding across the country despite reported minor violations.
The cessation of hostilities does not apply to designated terrorist organizations operating in Syria, including Daesh and al-Nusra Front, a group affiliated with al-Qaeda. Both groups are banned in Russia.
