North Korea fired a ballistic missile toward the North's eastern waters, South Korea's Joint Chiefs of Staff said on Thursday.

"It is believed the North Korea ballistic missile is a long-range ballistic missile fired at a high angle," the Joint Chiefs of Staff said in a statement.

The reported launch came a day after South Korea's military intelligence agency told lawmakers that North Korea has likely completed preparations for its seventh nuclear test. The intelligence said the North was close to testing a long-range missile capable of reaching the United States.

The Japanese Coast Guard also said North Korea had fired what appeared to be a ballistic missile. The Japanese government said the missile was expected to land at around 2336 GMT, some 300 kilometers (190 miles) west of Japan's Okushiri Island.

"Around 7:11 a.m. today (2217 GMT Wednesday) North Korea launched at least one ICBM-class ballistic missile from an area near Pyongyang toward the northeast," Japanese Defense Minister General Nakatani told reporters, adding that its flying distance was estimated at about 1,000 kilometers (620 miles) and its highest altitude more than 7,000 kilometers.

The missile had the "longest flying time" yet for North Korea, Nakatani said, adding that he thinks "it may be different from conventional missiles."

The United States was quick to condemn the launch of the ballistic missile by North Korea. US officials said they believed the launch was that of an intercontinental ballistic missile [ICBM] but did not say how they had reached that assessment.

North Korea ramps up weapons program

Since 2022, Pyongyang has sharply increased the pace of its weapons tests.

In September 2023, North Korea enshrined nuclear weapons in its constitution, with the motion unanimously rubber-stamped in parliament.

North Korean leader Kim Jong Un said at the time it was "very important" to "accelerate the modernization of nuclear weapons in order to hold the definite edge of strategic deterrence."

Last month, North Korea said Kim had supervised the testing of two different missiles, including one that would carry a "super-large conventional warhead."

The other missile tested was referred to as a "strategic" cruise missile, indicating that it could have been testing nuclear capacity.

US and South Korea wary of North Korean troops in Russia

Thursday's development came just a few hours after US Defense Secretary Lloyd Austin alleged that North Korean troops wearing Russian uniforms and carrying Russian equipment, were en route to the Russian region of Kursk, near Ukraine.

Speaking alongside South Korean Defense Minister Kim Yong-hyun, Austin said "the likelihood is pretty high" that Moscow will deploy North Korean troops in combat.

Concerns are growing over North Korea's deployment of as many as 12,000 troops to aid Russia over its invasion of Ukraine.