SEOUL, South Korea: In a surprise move, North Korea launched a “barrage” of unidentified short-range missiles into the Sea of Japan, American and South Korean sources said.
South Korean military said North Korea has fired "several" short-range missiles, increasing count from previous one.
The White House said it was "aware" of North Korea's actions, and will continue to "monitor".
The missiles were fired from the Hodo peninsula in the east of the country, said South Korea's Joint Chiefs of Staff.
If confirmed, it will be the first missile launch since Pyongyang tested an intercontinental ballistic missile in November 2017.
Last month, Pyongyang said it had tested what it described as a new "tactical guided weapon".
That was the first test since the Vietnam summit between the North Korean leader, Kim Jong-un, and US President Donald Trump, which ended without agreement.
President Trump walked away from what he described as a bad deal offered by Kim Jong-un in Hanoi in February.
Firing a short range missile would not violate North Korea's promise not to test long range or nuclear missiles.
But Pyongyang appears to be growing impatient with Washington's insistence that full economic sanctions remain until Mr Kim takes serious steps to dismantle his nuclear weapons programme, says the BBC's Laura Bicker.
"We are aware of North Korea's actions tonight," said White House spokeswoman Sarah Sanders. "We will continue to monitor as necessary."
Nuclear test pledge
North Korea "fired a number of short-range missiles from its Hodo peninsula near the east coast town of Wonsan to the north-eastern direction from 09:06 (00:06 GMT) to 09:27," the South's Joint Chiefs of Staff said in a statement.
The missiles flew for between 70km and 200km (45-125 miles) before landing in the Sea of Japan, they added.
Hodo has been used in the past for launching cruise missiles and long-range artillery testing.
According to the North Korea news agency (KCNA), April's test of a new "tactical guided weapon" was overseen by Mr Kim himself.
It said the test was "conducted in various modes of firing at different targets", which analysts believe means the weapon could be launched from land, sea or air.