North Korea fired «several rounds of cruise missiles» early Saturday, the South Korean military said, as the secretive communist state remained silent on the fate of a US soldier it had detained.

South Korea’s Joint Chiefs of Staff said in a statement that the speedboats were fired into the Yellow Sea starting at 4 a.m. Saturday (3 p.m. Friday ET). It did not say how many missiles were fired or how far they flew.

“South Korean and US intelligence officials are undergoing detailed analysis to obtain more information,” the statement said.

The shooting came after a US soldier, Pvt. Travis King, 23, 2nd Class, fled across the border during a tour of the Joint Security Area, a UN-administered site between the north and south, on Tuesday.

North Korea has so far remained silent on King’s status.

Defense Department spokeswoman Sabrina Singh said Wednesday that the United States had been in contact with Sweden, through which Washington maintains embassy-level relations with North Korea, for information on King’s whereabouts and well-being, but had not received a response.

Before fleeing to the North, King had spent 48 days in a prison in Cheonan, a city about 50 miles south of the South Korean capital Seoul, after failing to pay a $4,000 fine on charges that included damaging public property.

However, Saturday’s missile barrage, which appeared to be a protest against the deployment of a US nuclear-armed submarine to South Korea on Tuesday, came at a critical time in relations between North Korea and its neighboring US allies.

On Thursday, while keeping quiet about King, North Korean Defense Minister Kang Sun Nam issued a veiled threat suggesting that the docking of the USS Kentucky could be the reason for a nuclear attack by the North.

The deployment of the Kentucky off the coast of Busan was the first visit by a nuclear-armed US submarine since the 1980s, according to the South Korean Defense Ministry.

The rogue state also fired two missiles from its opposite coast into Japan on Thursday and last week tested its latest Hwasong-18 intercontinental ballistic missile, as leader Kim Jong Un vowed to improve his nation’s nuclear deterrent capabilities.

The isolated communist nation has long threatened to launch intercontinental ballistic missiles in self-defense amid what it calls active Western plans to launch an attack on it.

In an April meeting between President Joe Biden and South Korean President Yoon Suk Yeol, Biden warned that «a nuclear attack by North Korea against the United States or its allies and partners is unacceptable and will result in the end of any regime that takes such action.»

Biden and Yoon are scheduled to meet again at Camp David next month, along with Japanese Prime Minister Fumio Kishida.

stele kim and Associated Press contributed.