Pakistan, July 30 -- Iran launched a barrage of missiles at American forces in the Middle East early Wednesday as the US partnered with Saudi Arabia to strike Tehran-backed militias in neighboring Iraq, killing at least 20 fighters.

Six Iranian advisers were also killed in the US-Saudi strike, two Iraqi militia officials told the Associated Press. They spoke on condition of anonymity because they were not authorized to comment publicly.

The flare-up on multiple fronts, after several days of relative calm, raised the risk of a return to all-out war. It also underscored the difficulty of winding down a five-month conflict that has jolted the world economy and is unpopular among Americans. The fighting was also likely to add to concerns th...