The Joint Chief of Staff (JCS) of the South Korean army said that the projectile was “assumed to be a missile of the Scud series” and had a flight distance of 450 kilometres.
It was launched eastward near the city of Wonsan, 200 kilometres east of Pyongyang, at around 5:39 am (2039 GMT Sunday), the JCS said.
In an emailed statement, the US Pacific Command said that the “short range ballistic missile” was tracked for six minutes until it landed in the Sea of Japan.
“We continue to monitor North Korea’s actions closely,” the statement said, adding that the US has an “ironclad commitment to the security of our allies in the Republic of Korea and Japan.”
The launch did not pose a risk to North America, US Pacific Command said.
Japan’s top government spokesman condemned the launch, saying the missile had entered Japan’s exclusive economic zone but there were no immediate reports of damage to aircraft or ships in the area.
“We cannot tolerate repeated provocations. We sternly protested against North Korea and condemned it (the launch) in the strongest terms,” Chief Cabinet Secretary Yoshihide Suga told a press conference, according to the Kyodo news agency.
Japanese Prime Minister Shinzo Abe also called on officials to gather further information on the launch while in Seoul, South Korean President Moon Jae In ordered a Monday morning meeting of the country’s national security council.
In Washington, a National Security Council spokesman said the US government was aware of reports of a projectile launch, adding that “the president has been briefed.”
North Korea has repeatedly launched missiles in recent months despite international criticism.
On May 21, the hermit kingdom launched a ballistic missile that travelled about 500 kilometres before falling into waters off its east coast.
Two days later, South Korean troops fired warning shots at an “unidentified object” that flew across the heavily fortified border with North Korea, the South Korean military said.
US President Donald Trump and Japan’s prime minister Abe agreed Friday, on the sidelines of the Group of Seven meeting in Sicily, to increase sanctions on North Korea amid concerns that the dictatorship is developing a nuclear weapons programme.
The United States vowed to cooperate with Japan and South Korea “to increase pressure on North Korea and demonstrate that North Korea’s current path is not sustainable,” a statement from the White House said.
The US military says it is planning to test its ability to shoot down long-range intercontinental ballistic missiles (ICBMs) in light of North Korea’s continued development of its missile programme.
Trump has also warned that the US could take unilateral action against North Korea in retaliation.