WASHINGTON, March 10 (Reuters) - A drone struck a major U.S. diplomatic facility in Iraq on Tuesday in suspected retaliation by pro-Tehran militias over the U.S.-Israeli war on Iran, the Washington Post reported, citing an unidentified security official and an internal U.S. State Department alert. The strike hit the diplomatic support center, a logistical hub for U.S. diplomats near Baghdad airport and Iraqi military bases, the Post reported.