China sent a record number of warplanes across a U.S.-drawn boundary in the Taiwan Strait—a move that comes as the new president of the archipelago mulls a trip that may include a stop in America. Some 56 aircraft crossed the so-called median line as of early Thursday, the Ministry of National Defense in Taipei said on the X social media site. Taiwanese aircraft, naval vessels and missile systems were used “in response” to the flights by the People’s Liberation Army, the military added,...