"The imminent threat of physical harm to U.S. military personnel due to civil insurrection, civil war, terrorism, or wartime conditions has been significantly reduced in many countries. As a result, IDP will be discontinued in those areas," the Pentagon said in a statement.

Among the more than 20 locales dropped from the new list, which takes effect June 1, is Bahrain, headquarters to the U.S. Fifth Fleet, plus the waterways of the neighboring Gulf, Arabian Sea and Red Sea, where the Navy regularly deploys its ships.