North Korea fired two projectiles Thursday that appeared to be short-range missiles, the South's military said, just days after it launched a presumed ballistic missile amid stalled denuclearization talks with the United States.

The projectiles were fired from the northwestern area of Kusong in an easterly direction, one of them at 4:29 p.m. and the other at 4:39 p.m., flying about 420 km and 270 km, respectively, before landing in the Sea of Japan, the Joint Chiefs of Staff said.

"Our military has strengthened surveillance and vigilance in case of a further launch from North Korea, and has maintained a full-fledged posture in close coordination with the United States," the JCS said.