A U.S. Air Force general is warning that a major annual military exercise with Gulf Arab countries is at risk over the ongoing diplomatic crisis engulfing Qatar.

Lt. Gen. Jeffrey L. Harrigian said American officials are still looking at options over the annual Eagle Resolve exercise.

The exercise, held since 1999, sees countries in the Gulf Cooperation Council send forces alongside Americans to simulate working as a multinational force in battle. This year's Eagle Resolve exercise, held in Kuwait in March, involved 1,000 U.S. troops.

Harrigian, the top official at U.S. Air Force Central Command in Qatar, told journalists in Dubai on Friday that already a leadership course was cancelled over the crisis.

The Associated Press in October first reported exercises were at risk over the monthslong dispute.