This photo provided by the North Korean government shows a test of weapon systems.
The announcement on the "strike drill", which the Korean Central News Agency said took place Saturday and was overseen by Kim Jong Un, came after US President Donald Trump voiced confidence that the North Korean leader would not "break his promise" even as nuclear talks have been deadlocked.
KCNA said the tests in the East Sea, also known as the Sea of Japan, aimed to "estimate and inspect the operating ability and the accuracy of striking duty performance" of the weapons.
Kim was also evaluating "the combat performance of arms and equipment," according to KCNA.
Kim urged his troops to bear in mind "the iron truth that genuine peace and security are ensured and guaranteed only by powerful strength," it added.
On Saturday, the North also fired "a number of short-range projectiles" from Hodo peninsula near the east coast town of Wonsan starting at 9:06 am (0006 GMT), the South's Joint Chiefs of Staff said in a statement.
The projectiles traveled northeast from 70 to 200 kilometers (45 to 125 miles) toward the East Sea.
In an earlier statement, it had said Pyongyang launched an unidentified short-range missile.
"Anything in this very interesting world is possible," Trump tweeted in reaction to the launches announced by the South Koreans.
"But I believe that Kim Jong Un fully realizes the great economic potential of North Korea, & will do nothing to interfere or end it," he added.
"He also knows that I am with him & does not want to break his promise to me. Deal will happen!"
Since their historic summit meeting in Singapore in 2018, Trump has said Kim remains committed to the "complete denuclearization" of the Korean peninsula.
He has insisted the two leaders remain close even after their follow-up meeting in Hanoi collapsed in February, and that Kim would maintain his moratorium on long-range missile and nuclear tests.
But with negotiations lagging, the North appears to be testing the US side.
The launches followed last month's test-firing of very short range tactical weapons, and it came days after a senior North Korean diplomat chastised US Secretary of State Mike Pompeo for making "foolish and dangerous" comments in nuclear talks with the North.
The missiles, launched from near the coastal city of Wonsan, flew about 430 km (267 miles) out over the sea, reaching an altitude of 50 km (30 miles), before splashing down,
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