North Korea launched four short-range missiles, the first such action in more than nine months, disrupting a period of easing tensions with the South.

The missiles were fired into the sea from North Korea’s east coast shortly before 6 p.m. local time, and had a range of 200 kilometers (124 miles), South Korea’s Defense Ministry said.

The launches came days after the two countries wrapped up the first reunions in more than three years of families divided by the 1950-1953 Korean War, and held bilateral talks on improving ties. Still, the North has denounced the annual U.S.- South Korea drills that began this week as a rehearsal for war, and the exercises have previously prompted reaction from Kim Jong Un’s regime.

Key Resolve and Foal Eagle, the two sets of drills between the U.S. and South Korea, will draw thousands of U.S. troops from abroad, ending on March 6 and April 18, respectively, according to U.S. Forces Korea. The U.S. maintains 28,500 troops in South Korea to help rebuff any attack from the North.

South Korea previously said a North Korean naval boat crossed the disputed Yellow Sea boundary on Feb. 24, turning back after the South issued warning messages via radio.

North Korea last fired short-range missiles in May, testing six of them in a period of three days in defiance of global sanctions. The North said at the time it was exercising its right to test-fire rockets as part of regular military drills.

South Korea’s defense ministry said it is still analyzing why North Korea launched the missiles.