An Islamic State convoy stuck in the middle of the Syrian desert for more than two weeks because of American airstrikes finally reached eastern Syria late Wednesday night, according to reports from citizen journalist groups in the area. The convoy reached territory held by the Islamic State, despite vows by the American-led coalition fighting the group that it would not be allowed to do so.

There was no official confirmation of the reports, which were from credible contacts in eastern Syria that were monitored in Damascus, the capital. A spokesman for the coalition, Col. Ryan Dillon, said early Thursday in Baghdad that he had no comment on the matter. The reports said that the remnants of the convoy, which originally carried 600 Islamic State fighters and their family members, had reached Mayadin in eastern Deir al-Zour Province, near the border with Iraq.

The coalition announced last Friday that it was removing surveillance aircraft from the vicinity of the convoy at the request of the Russian authorities, because Russian warplanes were involved in supporting a Syrian Army advance into Deir al-Zour Province. That advance took the Syrian forces directly past the area where the convoy was stranded, near the town of Sukhna.

The convoy, originally consisting of 17 vehicles — buses and ambulances — and escorts from the Lebanese Hezbollah militia group, had been stuck near Sukhna, on the main highway from Damascus to the city of Deir al-Zour, where the Syrian Army claimed it ended a blockade by the Islamic State last week. The convoy was whittled down to 11 vehicles when six returned to Syrian government territory in western Syria, coalition officials said.