WASHINGTON—Lasers have targeted pilots of American military aircraft operating over the western Pacific Ocean more than 20 times in recent months, U.S. officials say, following a series of similar incidents in which Pentagon officials said Chinese personnel used lasers against U.S. pilots in East Africa.

Officials said all of the incidents occurred in and around the East China Sea, typically where the Chinese military or other Chinese civilians operate. The laser signals directed at American aircraft appeared to be coming...