BAGHDAD (AP) — Iraq's move this week to place Iranian-backed militias under the command of the armed forces is a political gamble by a prime minister increasingly caught in the middle of the rivalry between Iran and the U.S, the two main power brokers in Iraq.

Facing pressure from the U.S. to curb the militias, the move allows Prime Minister Adel Abdul-Mahdi to demonstrate a tough stance ahead of a planned visit to Washington. It is unlikely, though, that he will be able to rein in the powerful Iran-supported militias, and he risks coming off as a weak if he doesn't.

Besides having built credibility as an effective force against the Islamic State group, the mainly Shiite militias are a significant political force, with government ministers and 48 seats in the 329-member parliament.