SEOUL AND TOKYO - The Republic of Korea and Japan have denounced Monday's launch of four ballistic missiles by the Democratic People's Republic of Korea as a grave provocation.

In Seoul, Prime Minister Hwang Kyo-ahn, who is serving as caretaker president following the impeachment of President Park Geun-hye, called the launch a direct challenge to the international community.

And in Tokyo, Prime Minister Shinzo Abe described the move a "serious provocation".

Seoul's Foreign Ministry said the DPRK's ballistic missile launches blatantly and clearly violates the UN Security Council resolutions while threatening peace and stability in the Korean Peninsula and the entire international community.

Under the UN resolutions, Pyongyang is banned from testing any ballistic missile technology.

The statement said Pyongyang should realize the fact that repeated provocations and "fanatic" adherence to nuclear and missile developments will speed up the country's isolation and self-destruction.

Japanese leader Abe confirmed the missile launches during an Upper House Committee session on Monday, saying "the launches clearly show that North Korea has reached a new dimension of threat and the repeated launches are serious provocation to our security".

While saying there were no immediate reports of damage to ships, vessels, or aircraft flying in the vicinity of the missiles' flight path, Japan's top government spokesman Yoshihide Suga said in Tokyo that the DPRK's launch was a "grave threat to national security", and Japan would be fully on alert for any future contingencies.

ROK's chief negotiator of the Six-Party Talks also held emergency phone talks with his US and Japanese counterparts following the missile launches, Seoul's Foreign Ministry said.

Possible retaliation

The launches came as a possible retaliation to the annual US-ROK springtime war game that kicked off on March 1. Pyongyang has denounced it as a dress rehearsal for northward invasion.

The Foal Eagle field training exercise was scheduled to last by the end of April, mobilizing US strategic assets such as a nuclear-powered aircraft carrier and stealth fighter jets.

About 10,000 US troops, including US Forces Korea, were scheduled to be mobilized for the drill together with 290,000 ROK soldiers.

It would be almost the same as the largest spring war game carried out in 2016.

On Feb 12, Pyongyang successfully test-launched a new type of Pukguksong-2 intermediate range ballistic missile in the launch supervised by DPRK leader Kim Jong-un.

Expectations had been running high for the DPRK's test-firing of a new intercontinental ballistic missile in the near future based on the IRBM technology, but the ROK military said the missiles launched on Monday were unlikely to be new ICBMs of the DPRK.