North Korea has test-fired 25 rockets into the sea, South Korea's Defence Ministry has said, the latest in a series of launches that have provoked criticism from Seoul and Washington.
The rockets were fired off the North's east coast and flew about 70km into the sea, a ministry spokesman said.
"Following the North's rocket launch at 6:20pm (09:20 GMT), our military has maintained a close watch for possible North Korean provocations," the spokesman said on Sunday.
South Korea called the launches a "reckless provocation" while Washington urged Pyongyang to halt the tests immediately, saying they risked inflaming regional tensions.
"We urge North Korea to stop provocative activities that will heighten military tension across the border," the spokesman added.
North Korea has defended its drills as preparation for an invasion.
Sunday's rocket launch came two days after the North's National Defence Commission threatened to demonstrate its nuclear deterrence.
"Additional measures will be taken to demonstrate its might one after another as long as the US nuclear threat and blackmail persist as now", the commission said in a statement.
Analysts told the AFP news agency the comments could indicate the regime is preparing to carry out a fourth atomic test.
The North carried out nuclear tests in 2006, 2009 and in February 2013.
Despite tensions over the North's missile tests, cross-border ties have improved as of late, with the two Koreas recently holding the first reunion for more than three years for familes divided by the Korean war.