SEOUL, South Korea — North Korea fired several unidentified short-range projectiles into the sea off its eastern coast on Saturday, the South Korean Joint Chiefs of Staff said, a likely sign of Pyongyang’s growing frustration at stalled diplomatic talks with Washington meant to provide coveted sanctions relief in return for nuclear disarmament.

South Korea’s military has bolstered its surveillance in case there are additional weapons launches, and South Korean and U.S. authorities are analyzing the details.