The official said that the projectile is similar to the two launched by North Korea earlier this week which were assessed to be short-range ballistic missiles. The South Korean Joint Chiefs also later confirmed the launch of unknown short-range projectiles at 2:59 a.m. and 3:23 from South Hamgyong Province into the East Sea.
This is the third launch by North Korea in the last two weeks alone. U.S. officials have said these launches appear to be North Korea's protest to joint U.S.-ROK military exercises set to begin later this month.
Thursday's launch was first reported by CNN.
The U.S. ambassador to South Korea Harry Harris said earlier on Thursday that the U.S. was "not overly bothered" with the latest tests but more focused on the "greater issue which is bringing peace to the peninsula and achieving final, fully verified denuclearization of North Korea."
Harris said Pyongyang has long denounced U.S. and South Korean military exercises, adding that this month's drills have been readjusted and scaled down.
This latest test comes as the United Kingdom, France and Germany condemned North Korea's ballistic missile launches from earlier this week following a closed United Nations Security Council briefing. The countries called the tests a violation of U.N. sanctions and urged Pyongyang to meet the U.S. at the negotiating table instead.
Secretary of State Mike Pompeo told reporters in Thailand on Thursday that the U.S. stands "ready to continue our diplomatic conversations with the North Koreans."
He expressed regret that he would not meet his North Korean counterparts during his visit to Bangkok but said he's still "optimistic that that will happen before too long and we're looking forward to the chance to reconnect with them," calling on North Korean leader Kim Jong Un to "deploy his team."
One month ago, during President Donald Trump's historic visit to the Demilitarized Zone between North and South Korea, Kim agreed to working-level negotiations in a matter of weeks, but after weeks of waiting and preparing, those meetings have not taken place.
As President Donald Trump was leaving the White House for a campaign rally Thursday afternoon, he was asked if Kim was testing him and Trump said that it was very much under control.