U.S. diplomats and troops in Iraq and Syria were targeted in three rocket and drone attacks in the past 24 hours, U.S. and Iraq officials said, including at least 14 rockets hitting an Iraqi air base hosting U.S. forces, wounding two American service members, writes Reuters.

While there were no immediate claims of responsibility for the attacks - part of a wave targeting U.S. troops or areas where they are based in Iraq and Syria - analysts believed they were part of a campaign by Iranian-backed militias.

Iraqi militia groups aligned with Iran vowed to retaliate after U.S. strikes on the Iraqi-Syrian border killed four of their members last month.

Two people were slightly wounded in the rocket attack on the Ain al-Asad air base in western Iraq, said coalition spokesman U.S. Army Colonel Wayne Marotto. The rockets landed on the base and its perimeter. He said earlier that three people were wounded.