New Delhi, March 15 -- Pro-Iranian hackers are targeting sites in the Middle East and starting to stretch into the United States during the war, raising the risk of American defense contractors, power stations and water plants being swept into a wave of digital chaos that could expand if Tehran's allies join the fray.

Hackers supporting Iran claimed responsibility for a significant cyberattack Wednesday against U.S. medical device company Stryker. Since the war began Feb. 28, they also have tried to penetrate cameras in Middle Eastern countries to improve Iran's missile targeting. They have targeted data centers in the region, as well as industrial facilities in Israel, a school in Saudi Arabia and an airport in Kuwait.

Iran has investe...