Syrian rebels claimed on Monday, August 13 that they had brought down a Syrian fighter jet for the first time, posting a video of what they said was proof, while the United Nations said it had removed a third of its observers in advance of its mandate expiring later this month, New York Times reported.

The rebels said they shot down the jet early on Monday in the eastern city of Deir Ezzour, according to activists. A 33-second video released by the Local Coordination Committees, an activist network based in different areas, shows a jet rushing across the screen before bursting into flames.

Both developments three weeks into a ground battle for Aleppo, and as fighting spreads in Damascus, Dara’a and other areas highlight the conflict’s recent spiral away from diplomacy and toward widening war.

After 17 months, Syria is being defined by confrontation, with no end in sight, said Gen. Babacar Gaye, Head of the United Nations Supervision Mission in Syria.

“It is clear that violence is increasing in many parts of Syria,” General Gaye said, noting that fighting had forced United Nations observers to leave Aleppo. “The indiscriminate use of heavy weapons by the government and targeted attacks by the opposition in urban centers are inflicting a heavy toll on innocent civilians.”