North Korea Launches Cruise Missiles Into Yellow Sea

North Korea fired several cruise missiles into the Yellow Sea around 4 a.m. local time on Saturday morning, according to South Korea’s Joint Chiefs of Staff. Seoul’s military didn’t reveal where the missiles were fired from or how far they traveled.

“Our military has bolstered surveillance and vigilance while closely cooperating with the U.S. and maintaining a firm readiness posture," JCS said.

The missile launches came as the USS Kentucky, an Ohio-class nuclear ballistic missile submarine, departed from South Korea on Friday. The American warship can stay submerged indefinitely and can fire nuclear warheads at targets thousands of miles away. Its port visit to the Korean Peninsula was part of the Washington Declaration, an agreement struck in late April between President Biden and South Korean President Yoon Suk Yeol.

Amid North Korea’s growing nuclear and missile threats, the U.S. promised to dispatch strategic assets to the region to reaffirm its commitment to protecting its allies. On Thursday, North Korea warned that such deployments of nuclear assets could meet the conditions for North Korea to use its nuclear weapons.

“The U.S. military must realize it has brought its strategic assets into far too dangerous waters," North Korean Defense Minister Kang Sun Nam said in a statement. Kang said the USS Kentucky’s visit was a “direct nuclear threat" to North Korea. South Korea’s defense ministry denied Pyongyang’s accusation, saying the submarine visit and other deterrence measures are a “fair defensive response to North Korea’s continuous nuclear and missile threat."

North Korea last fired cruise missiles from a submarine in March. Pyongyang’s state media said the underwater launch demonstrated the country’s diverse methods of conducting a nuclear strike.

Earlier this week North Korea fired two short-range ballistic missiles following a series of statements criticizing Washington’s dispatch of strategic assets to the Korean Peninsula. North Korea has repeatedly refused to engage in dialogue with the U.S. On Monday, Kim Yo Jong, the sister of North Korean leader Kim Jong Un, said Pyongyang would seek to restrain the U.S. with “sufficient exercise of force," ridiculing the Biden administration’s calls for dialogue.

U.S. officials have attempted to establish contact with North Korea through several channels, after a U.S. soldier crossed into North Korea on Tuesday during a tour of the Joint Security Area on the South Korean side. North Korea hasn’t responded.

Pyongyang has shown no interest in returning to disarmament talks, despite the Biden administration’s repeated offers to do so without preconditions. North Korea is preparing to celebrate a major holiday it calls Victory Day on July 27. Pyongyang will likely hold a military parade featuring military hardware to celebrate the holiday.

Write to Dasl Yoon at dasl.yoon@wsj.com