In its third round of launches since last week, North Korea fired the missiles consecutively on Monday night from about 11:55pm (14:55 GMT) to midnight (15:00 GMT) from an area near its capital, Pyongyang, South Korea’s Joint Chiefs of Staff said.
Both missiles travelled about 400km (248 miles) before landing in waters off the Korean Peninsula’s eastern coast, it said.
The South Korean military called North Korea’s missile launches a “grave provocation” that threatens regional peace and stability.
Japan’s defence ministry also reported the launch of what it said could be a ballistic missile by North Korea. There may have been multiple missiles launched, Japanese media reported, citing a Japanese government source.
The projectile is believed to have fallen outside Japan’s exclusive economic zone, Japanese public broadcaster NHK said, citing officials.
Japan’s coastguard urged vessels in affected areas to watch out for falling debris.
The launches came hours after South Korea’s navy said a nuclear-propelled US submarine – the USS Annapolis – had arrived at a port on Jeju Island.
The Annapolis, whose main mission is destroying enemy ships and submarines, is powered by a nuclear reactor but is armed with conventional weapons. The submarine mainly docked at Jeju to load supplies but Jang Do Young, a spokesperson for South Korea’s navy, said the US and South Korean militaries were discussing whether to arrange training involving the vessel.
The Annapolis’s visit came days after the USS Kentucky became the first US nuclear-armed submarine to come to South Korea since the 1980s.
North Korea reacted angrily to the Kentucky’s arrival, warning that such deployments could meet the criteria for its use of nuclear weapons. It also test-fired ballistic and cruise missiles in apparent demonstrations that it could make nuclear strikes against South Korea and US naval vessels.
Also on Monday, the US-led United Nations Command said it has started “a conversation” with North Korea about an American soldier who ran into North Korea last week across one of the world’s most heavily-fortified borders.
Andrew Harrison, a British lieutenant general who is the deputy commander at the UN Command, which oversees the implementation of the 1953 armistice that ended fighting in the Korean War, declined to comment about the state of the inquiry to North Korea or say what the command knows about Private Travis King’s condition.
“I am in life an optimist, and I remain optimistic,” Harrison said during a news conference in Seoul.
In Washington, DC, State Department spokesman Matthew Miller said North Korea had only “acknowledged” receiving the UN message last week and had not provided any information or commented further since then.
“There have been no new contacts since last week,” Miller said, adding that North Korea also had not responded to messages sent by US civilian or military officials.
North Korea has remained publicly silent about King, who crossed the border during a tour of Panmunjom while he was supposed to be heading to Fort Bliss, Texas, following his release from prison in South Korea on an assault conviction.
The US still has not been able to ascertain King’s condition, a senior administration official said on Monday in Washington, DC. Asked if US officials had a better understanding of whether King intended to defect, the official said they still had “no indication about what was going on in his mind that day”. The official was not authorised to comment publicly and spoke on the condition of anonymity.
King’s crossing came at a time of high tensions on the Korean Peninsula, where the pace of North Korea’s weapons demonstrations as well as the US and South Korea’s combined military exercises have intensified in a tit-for-tat cycle.
Pyongyang has launched more than 100 missiles since the start of 2022, while earlier in July, North Korean leader Kim Jong Un personally oversaw the firing of the country’s newest intercontinental ballistic missile, the solid-fuel Hwasong-18.
The US and South Korea, meanwhile, have expanded their combined military exercises and increased regional deployments of US aircraft and ships, including bombers, aircraft carriers and submarines.
The Koreas are still technically at war since they never signed a peace treaty following the 1950-1953 Korean War.
Their armistice becomes 70 years old on Thursday.
South Korea will mark the anniversary with solemn ceremonies honouring the dead, which will involve invited foreign war veterans, while North Korea, which celebrates the date as victory day for the “great Fatherland Liberation War”, is expected to hold huge festivities that will likely include a military parade in the capital, Pyongyang.
North Korea’s state-run Korean Central News Agency said on Monday that a Chinese delegation led by Li Hongzhong, the vice chairman of the standing committee of the country’s National People’s Congress, would attend the celebrations.