Bahrain hosts the U.S. Fifth Fleet and Central Command Naval Forces, responsible for patrolling the Gulf. The U.S. Navy has been building forces in the Gulf and deployed two carrier strike groups in 2007.

Several GCC states have been exercising to prepare for an attack by Iran, Middle East Newsline reported. They include Gulf Arab states with a significant U.S. troops, such as Kuwait, Qatar and Oman.

"Our partnership and cooperative approaches to complex situations are key to tackling any situation that either of us may be confronted with," U.S. Naval Support Activity emergency management office director Robert Massie said.

Under the scenario, an Al Qaida-type group or Iran attacked NSA in Juffair. The facility, which contains up to 3,000 troops, was said to have sustained a bombing in which 20 people were killed and 20 others were injured.

Officials said more than 800 U.S. sailors and Defense Department staffers participated in the exercise. Bahraini security forces and police provided perimeter security as U.S. Navy helicopters flew above in the largest drill in the kingdom in at least a decade.

"The exercise will test the capabilities of all participants to effectively manage the integration of critical command and control, security, and consequence management resources," the U.S. Navy said in a statement.

Officials said the exercise included NSA, U.S. Marine Corps Security Forces, Explosive Ordnance Disposal, Emergency Response Team and U.S. Naval Branch Health Clinic. They said ships were not employed for the exercise.

"Desert Sailor-07 was designed to bring the host nation and NSA/CNRSWA response elements together to function as a single crisis management team that will work together to solve any potential issues brought about through a mass-casualty scenario," Massie said.