The United States hopes defense meetings in Riyadh on Wednesday will help advance a long-standing goal of building a regional missile shield, bolstered by Israel's successful defense against waves of incoming Iranian missiles and drones last month, U.S. officials say.

But it's unclear whether Gulf allies have the same confidence the U.S. would rush to their defense, or if those allies are willing to take the steps needed to truly integrate their defenses in a region that has longed hedged its bets, according to former U.S. officials and experts.

The May 22 meeting in Riyadh of the U.S.-Gulf Cooperation Council (GCC) comes just over a month after the United States, Britain and other allies helped Israel knock down hundreds of missiles and drones, mostly launched from inside Iran.