North Korea launched two apparent short-range ballistic missiles on Friday, the South's military said, hours after Pyongyang vowed a “stronger and certain reaction” to U.S. sanctions over a spate of recent launches.

The South Korean military said the two missiles had been fired eastward from North Pyongan province, which borders China, and that they flew around 430 km (270 miles) at an altitude of 36 km. It said it had detected one of the missile launches at 2:41 p.m and the other at 2:52 p.m.

Japanese Defense Minister Nobuo Kishi, meanwhile, confirmed the launch of at least one apparent ballistic missile, saying that it flew around 400 km, presuming the trajectory was standard, and hit a peak altitude of around 50 km. The missile was believed to have fallen into waters outside Japan's exclusive economic zone, which extends 200 nautical miles (370 kilometers) from its coast into the Sea of Japan.