North Korea launches 2 short-range ballistic missiles amid tensions with US

North Korea has fired two short-range ballistic missiles into the sea off its east coast, South Korea’s military said, adding to a recent streak in weapons testing that is apparently in protest of the US sending major naval assets to South Korea in a show of force.

In its third round of launches since last week, North Korea fired the missiles just before midnight from an area near its capital, Pyongyang, South Korea’s Joint Chiefs of Staff said on Tuesday.

It said both missiles travelled around 400 kilometres (248 miles) before landing in waters off the Korean Peninsula’s eastern coast.

Its statement called North Korea’s missile launches a "grave provocation" that threatens regional peace and stability.

Japan’s Prime Minister Fumio Kishida said his government lodged a protest to North Korea over the launches, which is usually conveyed through its embassy in Beijing.

He said Tokyo was doing its utmost for surveillance while stepping up trilateral security cooperation with Washington and Seoul.

No damage has been reported related to the missiles, which, according to Japan's Defence Ministry, fell outside the country's exclusive economic zone.

US submarine arrives in South Korea

The launches came hours after South Korea’s navy said a nuclear-propelled US submarine — the USS Annapolis — arrived at a port on Jeju island.

That underscored the allies' efforts to boost the visibility of US strategic assets in the region to intimidate the North.

Last week, the USS Kentucky became the first US nuclear-armed submarine to come to South Korea since the 1980s.

North Korea reacted to its arrival by test-firing ballistic and cruise missiles last week in apparent demonstrations that it could make nuclear strikes on South Korea and deployed US naval vessels.

Also on Monday, the American-led UN Command said it has started "a conversation" with North Korea about a US soldier who ran into the North last week across one of the world’s most heavily fortified borders.

Andrew Harrison, a British lieutenant general who is deputy commander at the U.N. 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 Pvt. Travis King’s condition.

"I am in life an optimist, and I remain optimistic," Harrison said during a news conference in Seoul.

In Washington, 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.