It is the first missile test conducted by North Korea since Donald Trump became US president.
“The South Korean government and the international community are working together to take punitive actions appropriate for this launch,” acting President Hwang Kyo-ahn said.
Trump, when asked by reporters about the missile launch, declined to comment. A White House spokesman said Trump was briefed on the launch.
Another source within the South Korean Defense Ministry told CNN that North Korea launched a projectile from North Pyongan Province. The missile traveled 500 kilometers (310 miles) and landed in the Sea of Japan, also known as the East Sea, sources said.
The launch involved an intermediate-range ballistic missile, a senior US official told CNN.
A State Department official said, “We are aware of reports and monitoring the situation carefully.”
South Korean security officials were holding an emergency meeting Sunday morning.
Step toward missile that can hit US?
Retired Lt. General Mark Hertling said the test was a step toward an intercontinental ballistic missile.
“That’s the goal of the North Korean politicians,” he said. “This intermediate ballistic missile is certainly dangerous. It has a greater range than some of the Musudan missiles that they have been testing prior to that. And it’s not only a concern for the United States to hit the mainland, but it also has concerns for all of our Asia partners.”
Hertling said because of the poor accuracy of North Korean missiles, missiles are fired at the Sea of Japan. North Korea wants to see how far the missile will fly and whether it will fall apart.
“They may have been testing some type of heat shield on the re-entry vehicle,” he said. “They may have been testing whether the missile could withstand G’s (gravity forces) given a payload.”
North Korea has never successfully tested an ICBM, despite repeatedly showing off at military parades what it claims are working missiles. Some experts have publicly doubted whether these long-range missiles are anything but mock-ups.
North Korea also has test-launched ballistic missiles from submarines.
North Korea is prohibited from carrying out ballistic missile launches under UN Security Council resolutions aimed in part at curbing the country’s development of nuclear weapons.
Pyongyang has been steadily working to improve its missile and weapons capability, conducting a fifth nuclear test in September.
North Korea conducted an unprecedented number of missile tests in 2016 and a satellite launch that experts said was a sign it has cleared significant hurdles toward ICBM technology.
Kim Jong Un’s regime hadn’t tested a ballistic missile since October 20.
The Musudan, its intermediate-range missile, can hit Guam, the location of a major US military base and a critical node in the defense of the western Pacific Ocean. It isn’t clear whether North Korea has the ability to put a nuclear warhead on the Musudan yet.
CNN’s Elise Labott, Elizabeth Landers, Joshua Berlinger and journalist Yoonjung Seo contributed to this report.