North Korea has reportedly launched at least 10 missiles of various types on Wednesday, prompting the South to urge its citizens on a nearby island to take shelter.
"North Korea fired at least 10 missiles of various types today towards the east and west," South Korea's Joint Chiefs of Staff said.
The launch had South Korean officials sound a rare air raid warning for the island of Ulleungdo, JCS said, telling residents to "evacuate to the nearest underground shelter."
The Japanese coastguard also warned the vessels sailing in the waters to take care.
Both the South and Japan called national security meetings following the launch.
"As we see tensions rising in the Korean Peninsula, I would like to hold a national security meeting as soon as possible," Japanese Prime Minister Fumio Kishida told reporters.
Hours earlier, North Korea warned the US and the South will “pay the most horrible price in history” amid their ongoing aerial drills.
The war games, dubbed Vigilant Storm, feature nearly 240 warplanes conducting about 1,600 sorties, US Air Force said in a recent statement, boasting that the exercises were unprecedented in their size.
On Monday, North Korea issued a strongly-worded message of caution aimed at the US and the South, warning them against continuing their joint military drills and vowing more powerful response to the US's provocations.
"The situation in the Korean Peninsula and its vicinity has entered the serious confrontation phase of power for power again due to the ceaseless and reckless military moves of the US and South Korea," North Korea's Foreign Ministry said in a statement that was carried by the country's official KCNA news agency.
"If the US continuously persists in the grave military provocations, the DPRK will take into account more powerful follow-up measures," the statement added, using the initials of the North's official name.
Washington and Seoul have markedly stepped up their muscle-flexing near the North's maritime border and airspace, as means of deterring another nuclear test by Pyongyang, which conducted its last such test in 2017.
North Korea, on the other hand, considers the drills to be an exercise for a pending invasion, and has been conducting a flurry of back-to-back missile launches, artillery fire drills, and aerial exercises since the beginning of this year.