Defense Secretary Chuck Hagel faces a tough challenge as he looks to reassure nervous allied Gulf nations that the U.S. will continue its strong military support to the region, even as world powers move forward on the nuclear pact with Iran.

Hagel is to speak later this week to a gathering of Gulf leaders. U.S. officials say he will stress America's commitment to the region, including sales of military weapons and efforts to improve the region's ability to defend itself. The officials who spoke on condition of anonymity because they were not authorized to discuss the visit publicly.

His visit comes less than two weeks after international leaders reached a deal with Iran freezing parts of its nuclear program in exchange for some relief from crippling Western economic sanctions.