North Korea fired two short-range ballistic missiles into its eastern sea, South Korea’s military said Tuesday, adding to a recent streak in weapons testing that is apparently in protest of the U.S. 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 consecutively between around 11:55 p.m. local time Monday and midnight from an area near its capital, Pyongyang, according to South Korea’s Joint Chiefs of Staff. It said both missiles traveled around 400 kilometers (248 miles) before landing in waters off the Korean Peninsula’s eastern coast and that the South Korean and U.S. intelligence agencies were analyzing the launches.

Japan’s Coast Guard urged vessels in affected areas to watch out for falling debris but there were no immediate reports of damage.

The South Korean Joint Chiefs of Staff in a statement condemned North Korea’s missile launches as a “grave provocation” that threaten regional peace and stability, and said the South Korean and U.S. militaries are working together to tighten their monitoring of North Korean military activities.

The launches came hours after South Korea’s navy said a nuclear-propelled U.S. submarine — the USS Annapolis — arrived at a port on Jeju Island. That underscored the allies’ efforts to boost the visibility of U.S. strategic assets in the region to intimidate the North.

Last week, the USS Kentucky became the first U.S. 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 against South Korea and deployed U.S. naval vessels.

Also on Monday, the American-led U.N. Command said it has started “a conversation” with North Korea about a U.S. 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 the deputy commander at the U.N. Command, refused to say when the conversation started and whether the North Koreans responded constructively, citing the sensitivity of the discussions. He also declined to detail what the command knows about Pvt. Travis King’s condition.

“None of us know where this is going to end,” Harrison said during a news conference in Seoul. “I am in life an optimist, and I remain optimistic. But again, I will leave it at that.”

It wasn’t immediately clear whether Harrison’s comments referred to meaningful progress after the command last week confirmed its initial outreach, saying it was “working with” its North Korean counterparts to resolve the incident.

The U.N. Command, which was created to fight the Korean War, has remained in South Korea to supervise the implementation of the 1953 armistice that stopped the fighting in the conflict.

The contact happened through “mechanisms” set up under the armistice, Harrison said. That could refer to the so-called pink phone, a telephone line between the command and the North Korean People’s Army at the border truce village of Panmunjom, where King crossed.

The Koreas are still technically at war since a peace treaty was never signed. The U.S., which fought alongside the South Koreans and other allies during the war, never established diplomatic relations with the North, but the line is a common way they communicate.

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.

U.S. officials have expressed concern about his well-being and said previously that North Korea ignored requests for information about him.

Analysts say North Korea may wait weeks or even months to provide meaningful information about King to maximize leverage and add urgency to U.S. efforts to secure his release. Some say North Korea may try to wrest concessions from Washington, such as tying his release to the United States cutting back its military activities with South Korea.

King’s crossing came at a time of high tensions in the Korean Peninsula, where the pace of both North Korea’s weapons demonstrations and the United States’ combined military exercises have intensified in a tit-for-tat cycle.

In between the ballistic and cruise missile launches last week, North Korea’s defense minister also issued a veiled threat, saying the Kentucky’s docking in South Korea could be grounds for the North to use a nuclear weapon against it. North Korea has used similar rhetoric before, but the statement underscored how strained relations are now.

The United States and South Korea have expanded their combined military exercises and increased regional deployments of U.S. aircraft and ships, including bombers, aircraft carriers and submarines to counter the nuclear threats posed by North Korea, which has test-fired around 100 missiles since the start of 2022.

The Annapolis, whose main mission is destroying enemy ships and submarines, is powered by a nuclear reactor but is armed with conventional weapons. The Annapolis mainly docked at Jeju to load supplies, but Jang Do Young, a spokesperson for South Korea’s navy, said the U.S. and South Korean militaries were discussing whether to arrange training involving the vessel.

The armistice becomes 70 years old on Thursday, an anniversary South Korea plans to mark with solemn ceremonies honoring the dead that will involve invited foreign war veterans.

North Korea, which celebrates the day as victory day for the “great Fatherland Liberation War,” is preparing huge festivities that will likely include a military parade in the capital, Pyongyang, where leader Kim Jong Un may showcase his most advanced nuclear-capable missiles designed to target regional rivals and the United States.

North Korea’s state-run Korean Central News Agency said Monday that a Chinese delegation led by Li Hongzhong, vice chairman of the standing committee of the country’s National People’s Congress, will travel to North Korea to attend the celebrations.

Visits by foreign guests to North Korea have been extremely rare since the start of the pandemic, which prompted the North to seal off its borders to protect its poor healthcare system. North Korea since last year has been gradually reopening trade with China in an apparent effort to salvage a crippled economy damaged further by the previous two years of pandemic-related border controls.

(AP)