SEOUL, South Korea — North Korea on Tuesday launched two short-range ballistic missiles into the sea between the Korean Peninsula and Japan, days before the United States and South Korea were scheduled to begin a joint military exercise.

The launch marked the fourth test of projectiles in 13 days by North Korea.

The two missiles were fired from a province in the southwest of North Korea and flew 280 miles before splashing into waters off the North’s east coast, the South Korean military said in a statement.

The missiles looked like the short-range ballistic missiles that North Korea had fired on July 25, South Korean defense officials said, after analyzing their trajectory and other flight data.

In that test, North Korea launched two missiles that were similar to Russia’s Iskander short-range ballistic missile. North Korea said at the time that it had launched guided missiles that would be harder to intercept because they could be maneuvered during their flights.