SEOUL, South Korea — A North Korean ballistic missile fired from a submarine today flew about 310 miles in the longest flight by that type of weapon, Seoul officials said, a range that can place much of South Korea within its striking distance.

Seoul officials condemned the launch as an “armed protest” against the start of annual South Korean-U.S. military drills that North Korea calls an invasion rehearsal. The launch was also the latest in a series of missile, rocket and other weapon tests by North Korea, which is openly pushing to acquire a reliable weapon capable striking targets as far away as the continental U.S.

The missile fired from a submarine off the eastern North Korean coastal town of Sinpo reached into Japan’s air defense identification zone, according to Seoul and Tokyo officials. The U.S. Strategic Command said it tracked the submarine launch of the presumed KN-11 missile into the Sea of Japan.

South Korea’s Joint Chiefs of Staff said the launch showed an “improvement” in ability over previous similar missile tests. The distance is longer than ones recorded by other submarine-launched missiles launched by North Korea, and puts most of South Korea within its range