North Korea test-fired two ballistic missiles early Sunday, the Japanese and South Korean governments said, a day after denouncing a military exercise near the Korean Peninsula involving a U.S aircraft carrier for raising regional tensions.

Both missiles, which North Korea fired into waters to its east at around 1:47 a.m. and 1:53 a.m., fell outside Japan's exclusive economic zone after traveling an estimated 350 kilometers at a maximum altitude of 100 km, according to Japanese officials.

Since late September, North Korea has conducted missile tests at a pace never before seen. Before the recent cluster, there had been a test hiatus of almost four months.

The latest test, the 25th this year, came days after the nuclear-armed nation launched a ballistic missile over the Japanese archipelago for the first time in five years.

Senior Vice Defense Minister Toshiro Ino told reporters North Korean missile launches "threaten the peace and safety of our nation, the region and the international community...so we strongly condemn" them.

There were no reports of damage to aircraft or ships, he said, adding the government is analyzing the possibility the projectiles were submarine-launched ballistic missiles.

"We should continue to closely monitor future provocative actions," Prime Minister Fumio Kishida told reporters in the central Japan city of Suzuka.

Kishida said the government is still checking whether they were SLBMs.

The South Korean military said North Korea fired two short-range ballistic missiles from near the Munchon area on its east coast, with their top speed reaching Mach 5, or five times the speed of sound.

South Korea's presidential office convened a National Security Council meeting and warned North Korea that its flurry of weapons tests could further isolate it from the international community and eventually destabilize the regime.

The South Korean Foreign Ministry said its top nuclear envoy Kim Gunn had one-to-one phone conversations with his Japanese and U.S. counterparts and agreed Pyongyang's missile tests, using military exercises by Seoul and Washington as a pretext, are intolerable.

With Kim and Sung Kim, U.S. special representative for North Korea, Japan's Foreign Ministry said Takehiro Funakoshi reaffirmed their belief that the missile spree is a serious and imminent threat to the security of the region and a clear challenge to the international community.

The missile fired on Tuesday over Japan traveled 4,600 km, the longest distance ever for a projectile launched by North Korea, putting it within reach of the U.S. territory of Guam.

It led the U.S. nuclear-powered aircraft carrier Ronald Reagan to return to waters near the peninsula for further military exercises with South Korea.

A spokesman for North Korea's Defense Ministry on Saturday slammed the aircraft carrier's presence, describing it as "an event of considerably huge negative splash to the regional situation."

He said North Korea's armed forces are "seriously approaching the extremely worrisome development of the present situation."

The latest test, the seventh round of missile launches in two weeks, came after South Korea and the United States concluded a two-day naval exercise in the Sea of Japan on Saturday, the eve of the 77th anniversary of the founding of the North's ruling Workers' Party.

The Ronald Reagan also participated in drills with South Korea's navy from Sept. 26 to 29, before Japan joined the first anti-submarine exercise in five years involving the three countries.

The U.S. Indo-Pacific Command said it had assessed that Sunday's missile launch did not pose an immediate threat to U.S. territory or its allies but highlighted the "destabilizing impact" of North Korea's "unlawful" weapons programs.

The Japanese prime minister instructed officials to prepare for contingencies, do their utmost to swiftly provide necessary information to the public and ensure the safety of aircraft and ships, according to his office.

Still, fears remain that North Korea could engage in additional provocative actions, including its seventh nuclear test which would be its first since September 2017.

There are no signs that North Korea is willing to stop developing weapons that are banned under U.N. Security Council resolutions.

Last month, North Korean leader Kim Jong Un said Pyongyang will not yield to international economic sanctions and pledged that he will never give up the nuclear weapons the nation needs to defend itself from U.S. military threats.