Russia’s military intervention in the Syrian war has all but destroyed a deal agreed last month to halt fighting between warring sides in two areas of the west, unpicking a rare success for foreign-backed diplomacy in the four-year-long conflict.

Implementation of the deal agreed with UN help to extricate rebels from the town of Zabadani and trapped villagers from al-Foua and Kefraya has effectively been shelved following Russian air strikes in support of President Bashar al-Assad, three sources familiar with the talks told Reuters.

While local ceasefires in both locations continue to hold, this means it may be only a matter of time before fighting resumes there between insurgent groups on the one hand, and the Syrian military and its Lebanese ally Hezbollah on the other.

The bleak outlook for the deal fits into a broader picture of escalation, as deepening foreign involvement further complicates a conflict that has already killed 250,000 people and shattered a nation.

The deal brokered with Iranian and Turkish help followed a weeks-long offensive by the Syrian military and Shi’ite Islamist Hezbollah to capture the town of Zabadani near the Lebanese border from insurgents who are still holed up there.

The rebels including the Sunni Islamist group Ahrar al-Sham and the al Qaeda-linked Nusra Front had been waging a parallel attack on Kefraya and al-Foua, two Shi’ite villages in the northwestern province of Idlib.

“There’s a ceasefire now but that’s about it. The deal has become another victim of the Russian escalation. People have forgotten about implementation,” said a person with knowledge of the negotiations.