In Syria, a Monday deadline for anti-government fighters to retreat from a buffer zone around Syria’s last major rebel-held region in Idlib province has come and gone, with rebels refusing to surrender. The U.N. has warned a large-scale offensive could force some 800,000 people to flee and provoke a humanitarian catastrophe.

Elsewhere, Syria reopened a major commercial gateway into Jordan on Monday, simultaneously reopening a crossing into the Israeli-occupied Golan Heights territory.

Meanwhile, the BBC has published a new investigation documenting the extent to which chemical weapons helped Syrian President Bashar al-Assad turn the tide in the war. The study found the use of chemical weapons has been widespread, with at least 106 chemical attacks since 2013 and evidence in most of the attacks pointing to the Syrian government.