Joseph Votel, a retired U.S. general who once led the Defense Department Central Command responsible for the Middle East, said the U.S. should work with Israel and the Gulf nations to build a unified, regional defense system to protect all the countries from attacks by Iran and its militant allies.

“Iran is proving itself to be not just a threat to Israel, but to the entire region through its enabled proxy network,” said Mr. Votel, who now serves as a distinguished nonresident fellow at the Middle East Institute in Washington. “A strong, unified approach to addressing this threat, which is growing in frequency, would seem to be beneficial.”