SEOUL, SOUTH KOREA - A day after warning of more aggressive steps in response to increased military activity by the United States and its allies, North Korea on Friday fired an intercontinental ballistic missile that apparently prompted a U.S.-Japanese air base to issue a seek cover order.

The North Korean ICBM flew for more than an hour before splashing down in Japan's exclusive economic zone - in waters about 200 kilometers west of Hokkaido prefecture in northern Japan - according to Japanese officials.

On its Facebook page, the Misawa Air Base, a joint U.S.-Japanese military facility on the northern island of Honshu, said authorities issued a seek cover order as a precautionary measure, without mentioning the North Korean missile.

In Washington, the National Security Council condemned the launch as a "brazen violation of multiple UN Security Council resolutions [that] needlessly raises tensions and risks destabilizing the security situation in the region."

In response to the launch, South Korean President Yoon Suk Yeol ordered a strengthening of the U.S.-South Korea defense posture, including measures related to "extended deterrence," his office said in a statement."

Japanese Prime Minister Fumio Kishida said his country lodged a "strong protest" against North Korea, which he said has "repeated its provocations with unprecedented frequency."

"We absolutely cannot tolerate these actions," Kishida told reporters in Thailand, where he is attending a regional summit.

Japanese Defense Minister Yasukazu Hamada said the missile had the range to reach the U.S. mainland, adding it was capable of flying 15,000 kilometers.

No other details were immediately available, including what type of ICBM was launched by North Korea.

The launch comes a day after North Korean Foreign Minister Choe Son Hui vowed a "fiercer" action against the United States, Japan, and South Korea.

Choe's statement particularly took aim at a recent summit during which U.S., Japanese, and South Korean leaders agreed to cooperate more closely on deterring North Korea.

"Pyongyang is trying to disrupt international cooperation against it by escalating military tensions and suggesting it has the capability of holding American cities at risk of nuclear attack," said Leif-Eric Easley, a professor at Ewha University in Seoul.

North Korea has developed multiple types of ICBMs that are believed to be capable of reaching the United States. Analysts say continued testing is necessary to ensure the missiles meet technical specifications, including the ability to survive reentry into the atmosphere.

North Korea is banned from conducting ballistic missile tests of any range under multiple U.N. Security Council resolutions.

In recent weeks, North Korea has unleashed an unprecedented barrage of missiles, including some that have prompted air raid sirens and shelter warnings in Japan and South Korea.

North Korea says it is a response to the increased military exercises by the United States and its allies. Washington says the drills are necessary as a response to the North Korean tests.

It is the second consecutive day that North Korea has launched a ballistic missile. On Thursday, just hours after Choe's statement was released, North Korea launched a short-range ballistic missile that landed in the sea off its east coast.

North Korea has launched more than 70 ballistic missiles this year - by far a record - including multiple ICBMs.

At a Pentagon briefing Thursday, deputy press secretary Sabrina Singh said North Korea's continued launches are destabilizing the region, but said the United States remains committed to defending its allies.

"Our commitment remains strong to the Republic of Korea and Japan. We are always going to stand up for our allies and partners around the world, in particular in the region, and we've called on North Korea to stop these ballistic missile launches," she said.

For months, U.S. and South Korean officials have also warned that North Korea has completed preparations for what would be its seventh nuclear test since 2006.