North Korea launched a missile to the east early on Nov. 29, according to the South Korean military.
When CNN confirmed the launch with South Korean military representatives, they said it was still flying.
"North Korea fired an unidentified ballistic missile early this morning from Pyongsong, South Pyongan, to the east direction," an official from South Korea's Joint Chiefs of Staff told CNN. "South Korea's Joint Chiefs of Staff is analyzing more details of the missile with the U.S. side."
The South Korean military conducted a missile firing test minutes after the North Korean missile was launched.
The U.S. military described the North Korean action as a probable missile launch, and believed it to be an intercontinental ballistic missile.
"We are in the process of assessing the situation and will provide additional details when available," Pentagon spokesman Col. Rob Manning added.
The missile reportedly landed in the sea near Japan. The Japanese government ordered an emergency meeting of cabinet ministers.
The Pentagon said the IBM flew for approximately 620 miles and at a greater altitude than in previous tests, according to The Telegraph.
President Donald Trump was briefed on the situation while the North Korean missile was still in the air, according to a tweet from White House press secretary Sarah Sanders. She added that Trump was visiting Congress when reports reached him.
During a United Nations speech in September, Trump threatened to "totally destroy" North Korea if the U.S. was compelled to defend itself.
News of the missile launch broke hours after two U.S. government sources described by Reuters as authoritative stated that Pyongyang was days away from attempting its first launch since it fired a missile over Japan in mid-September.
The South Korean military also thought a new test was immanent, with an official telling Reuters that they had observed a number of recent engine tests.
Prior to the latest launch, Pyongyang had fired 22 missiles in 15 tests since February. U.S. officials believe North Korea could be able to mount a miniaturized warhead on a missile in 2018. This would mean Pyongyang could potentially attack the U.S. with a nuclear warhead.
The latest missile test comes after the U.S. placed North Korea on a list of sponsors of terrorism. The step enables the government to impose more sanctions on the country.
The North Korean government reacted to the move by describing it as a "serious provocation and violent infringement," Reuters reported.