Iraq, Caught Between Two Allies, Poised to Vote on U.S. Troop Presence

Iran-backed militias in Iraq demanded lawmakers attend a session of parliament to vote on the possible expulsion of U.S. troops from the country, after the killing of an Iranian general there put the country at the center of an escalating conflict between its two most important allies.

Inside the parliament hall Sunday, lawmakers chanted, “America out! Baghdad remains free!”

The vote poses a pivotal test to an American troop presence that has been instrumental in the defeat of Islamic State, even as powerful Iranian-backed factions have come to dominate the...