An ISIS convoy that had been stranded in the Syrian desert for two weeks reached militant-held territory in eastern Syria on Wednesday after a U.S.-led coalition stopped airstrikes on its route following a request from Russia.

The Wall Street Journal reported Wednesday that opposition activists said the convoy of buses was able to reach Deir Ezzour province, an ISIS-held area, after the coalition ended its aerial surveillance and airstrikes on the group.

Col. Ryan Dillon, the spokesman for the coalition in Iraq and Syria, could not confirm the buses reached their final destination and said the coalition had not had persistent surveillance on them for days.

The 11-bus convoy traveled to the area as part of a controversial deal brokered in August between Syria and Hezbollah, a Lebanese terror group. The deal gave safe passage to 600 people, including ISIS fighters and their families, across the Syrian desert from the Lebanese border in southwestern Syria and to the border with Iraq.

The deal angered the U.S. military, which deployed drones to pick off ISIS fighters when they left the convoy to relieve themselves.

“We were able to exploit it and take advantage,” Dillion said during a press conference in Baghdad last week.

A week ago, the U.S. military said it pulled back surveillance aircraft that had been watching the convoy at the request of Russian officials who cited a “deconfliction” agreement between Moscow and Washington, Pentagon officials said in a statement at the time.