North Korea Fires Ballistic Missile From Submarine, Again

North Korea launched a missile from a submarine in the waters off the country’s east coast Tuesday, U.S. and South Korean officials said.

The missile launch was detected at around 5 a.m. Wednesday Pyongyang time (4:30 p.m. Tuesday ET), a U.S. defense official said.

The missile was fired in the Sea of Japan off the city of Sinpo, and it flew about 300 miles before splashing down in the sea, the U.S. defense official said. The country's previous sub-launched missiles this year either blew up or traveled a far shorter distance.

JULY 20: North Korea claims to have simulated nuclear strikes on US ports, airfields 0:23

Kim Dong Jo, a spokesman for the presidential office in Seoul, said South Korea also tracked the test missile. He said the standing committee of the presidential National Security Council would convene Wednesday to discuss the launch.

The missile was most likely a KN-11 ballistic missile, the U.S. official said. U.S. Strategic Command said it tracked the missile and it posed no threat to the U.S.

"We strongly condemn this and North Korea's other recent missile tests, which violate U.N. Security Council Resolutions explicitly prohibiting North Korea's launches using ballistic missile technology," Strategic Command said in a statement.

Related: North Korean Diplomat Defects to South Korea, Seoul Says

North Korea has defied the resolutions barring ballistic missile tests. The country has conducted four nuclear tests, most recently in January.

Image: File photo of an underwater test-firing of a strategic submarine ballistic missile is seen in this undated photo released by North Korea's KCNA
An underwater test-firing of a strategic submarine ballistic missile is seen in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on April 24, 2016. KCNA / Reuters

The new test is the third submarine-launched ballistic missile launched by North Korea this year.

The last missile, launched on July 9, exploded in mid-air while a missile launched April 29 traveled about 30 km, or a little more than 16 and a half miles.

A South Korean military officer told NBC News Wednesday's test indicates North Korea is making progress. The officer said the launch was likely timed as a show of force amid planned South Korean-U.S. military exercises.

"We are warning North Korea sternly that today's test launch of SLBM is a serious challenge to the security of the Korean peninsula, as well as a serious violation of the U.N. Security Council's resolution," the military officer said. "We will swiftly and strongly respond to North Korea's provocation based on our combined forces' resolute military readiness."

Related: North Korea Says It Simulated Pre-Emptive Strikes on U.S. Targets

The U.N. and U.S. imposed new sanctions on North Korea after the Feb. 7 launch of a rocket that was claimed to be for a satellite but which was seen as a thinly-veiled intercontinental ballistic missile test.

North Korea's most recent nuclear test was claimed by the regime to be a miniaturized hydrogen bomb, but experts have doubted the claim.

MAY 6: Inside North Korea: Kim Jong-un Opens Historic Party Congress 2:04

The missile tests come amid tough talk from the isolated nation.

North Korea’s top diplomat said last month that the U.S. "crossed a red line" and effectively declared war by putting leader Kim Jong Un on a list of sanctioned individuals.

North Korea has also expressed outrage over the planned deployment of a U.S. missile defense system, the Terminal High Altitude Area Defense, in South Korea.