North Korea launched "several unidentified short-range projectiles" on Saturday, a South Korean military official told NBC News.
"We confirm that what North Korea launched today was not ballistic missiles," the official told NBC News.
The official said the projectiles were launched at about 9:06 a.m. to 9:27 a.m. Korean Standard Time from Wonsan's Hodo Bando area in a northeastern direction. The official said the projectiles traveled about 70 to 200 kilometers (about 43 to 124 miles).
Officials had originally said there was one missile launched.
"The National Security's chief, the Minister of National Defense, the head of the National Intelligence Service have gathered at South Korea's presidential office and are monitoring the current situation and are sharing information closely with the U.S. counterparts," a South Korean's presidential spokesperson told NBC.
The Associated Press reported that Japan's Defense Ministry does not see any immediate risk to the country's national security as the missiles did not enter the territory.
South Korean and U.S. authorities are analyzing the situation, the military official told NBC, adding that the South Korean military has upped its surveillance and on the look out for more launches.
A senior administration official told NBC that National Security Advisor John Bolton has "fully briefed" President Donald Trump on the situation.
White House press secretary Sarah Sanders said "We are aware of North Korea's actions tonight. We will continue to monitor as necessary."
The Pentagon did not immediately respond to CNBC's request for comment.
This incident comes a little over two weeks after Pyongyang said North Korean leader Kim Jong Un oversaw a test of a new type of tactical guided weapon.
Saturday's launch is the second time North Korea fired a missile since talks collapsed between Trump and Kim in February. The two men had met in Hanoi to discuss the possibility of denuclearizing the Korean peninsula, but those talks ended abruptly without a deal. That summit had followed the historic meeting between Kim and Trump in Singapore last June.
In April 2018, North Korea had pledged to cease its nuclear and long-range missile tests. But suspicions about that promise flared when satellite images surfaced suggesting that a long-range missile test site was undergoing "rapid rebuilding."
Saturday's missile launch risks reigniting tensions between Washington and Pyongyang.
The Trump administration has been pressing North Korea to abandon its nuclear weapons but so far Pyongyang has resisted. On Friday, Sanders said Trump pressed Russian President Vladimir Putin to encourage Kim to denuclearize. But the Russian leader responded by urging the U.S. to ease its sanctions on the isolated state.
The North Korean leader had his first meeting last week with Putin. The Kremlin said Friday that Putin discussed that meeting and his takeaways with Trump.
— CNBC's Amanda Macias contributed reporting.