North Korea launched an intercontinental ballistic missile, the regime’s first rocket launch since September, South Korean military officials said on Tuesday.

President Trump has been briefed while the “missile was still in the air on the situation in North Korea,” White House press secretary Sarah Huckabee Sanders said in a tweet.

The missile was fired from Pyongsong, north of the country’s capital of Pyongyang, near dawn on Wednesday, the South Korean Yonhap News Agency reported, citing military officials.

The Pentagon called it a “probable” missile launch and was assessing the situation, said spokesman Col. Robert Manning.

The Japanese government said the rocket flew for about 50 minutes and landed in the sea in its economic zone, according to media reports in Japan. A North Korean missile fired in August was airborne for only 14 minutes.

Minutes after the launch, South Korea fired off a missile in response, its military said.

US government experts said radio signals picked up recently by Japan indicated that Pyongyang was preparing a missile launch within the next couple of days.

Activity had also been detected at several missile bases.

North Korea, which is under heavy sanctions from the United States and the United Nations over its weapons development, last launched an ICBM into the Pacific over Japan on Sept. 15.

The firing comes as a South Korean official said Pyongyang has accelerated its nuclear program and could announce the completion of the program as soon as next year.

“North Korea has been developing its nuclear weapons at a faster-than-expected pace. We cannot rule out the possibility that North Korea could announce its completion of a clear force within one year,” Minister Cho Myoung-gyon told reporters in Seoul on Tuesday.

US experts said Pyongyang detonated a nuclear device in September and has been test-firing missiles as it works to develop a rocket capable of carrying a nuclear payload that could strike the US mainland.

​Trump, during a 12-day trip to five Asian countries earlier this month, called for a concerted effort from the nations to pressure Pyongyang and enforce the sanctions and pressure the country to abandon its nuclear ambitions.

When he returned to Washington, Trump labeled President Kim Jong Un’s government a state sponsor of terrorism — a designation that would allow his administration to level more penalties on the belligerent country.