The U.S. military on Friday pulled back surveillance aircraft that had been watching an 11-bus ISIS convoy filled with hundreds of militants and their family members -- at the request of the Russian government.

The ISIS convoy was given safe passage over 10 days ago to travel from the Lebanon-Syria border across the Syrian desert to the Iraqi border in a deal struck between Syria and Hezbollah, which angered the U.S. military.

Since the convoy departed, U.S. drones have picked off ISIS fighters when they left the convoy to relieve themselves, according to U.S. officials.

“We were able to exploit it and take advantage,” said Army Col. Ryan Dillon, a U.S. coalition spokesman Thursday during a press conference from Baghdad.

The Russian military requested U.S. drones depart the area through the “de-confliction” line, as Russian-backed Syrian forces battle to recapture the ISIS-held city of Deir ez-Zor, located in eastern Syria.

The U.S. official was confident the U.S. military would pick up surveillance of the ISIS fighters in the future and said they would not threaten U.S. military forces located in other parts of Syria.

A U.S. Army general said he would hold the Assad regime in Syria responsible for dealing with the convoy.

"The regime's advance past the convoy underlines continued Syrian responsibility for the buses and terrorists. As always, we will do our utmost to ensure that the ISIS terrorists do not move toward the border of our Iraqi partners," said Brig. Gen. Jon Braga, director of operations for the coalition.

A week ago the outgoing top U.S. commander in Iraq suggested he had no intention of letting this convoy make it across the desert.

“When ISIS came out to link up with them, we started striking ISIS," said Lt. Gen. Stephen Townsend. “We have struck every ISIS fighter and/or vehicle that has tried to approach that convoy, and that -- will continue to do that.”

Townsend said the U.S. coalition did not target any civilians in the convoy, but now that there is no surveillance on the convoy there is no stopping the convoy from moving again.