Gen. Kim Seung-kyum, right, the South Korean Joint Chiefs of Staff chairman, and Gen. Paul LaCamera, second from right, the commander of the South Korea-U.S. Combined Forces Command, visit the U.S. nuclear-powered aircraft carrier Ronald Reagan in the East Sea, Tuesday, in this photo provided by the JCS. Yonhap

Top South Korean and U.S. military officials on Tuesday boarded the USS Ronald Reagan aircraft carrier partaking in a combined naval exercise in the East Sea, Seoul officials said, in an apparent display of the allies' unity against North Korean threats.

Seoul's Joint Chiefs of Staff Chairman Gen. Kim Seung-kyum and Gen. Paul LaCamera, the commander of the South Korea-U.S. Combined Forces Command, visited the nuclear-powered carrier that arrived here on Friday to join the allies' first naval drills near the peninsula in five years.

The four-day exercise kicked off on Monday amid growing concerns that Pyongyang could engage in provocative acts, such as a nuclear test or a submarine-launched ballistic missile.

Aboard the carrier, Kim and LaCamera received a briefing on the ongoing exercise, for which the allies deployed more than 20 vessels, including the nuclear-powered USS Annapolis submarine as well as key South Korean assets such as the 7,600-ton Aegis destroyer Seoae Ryu Sung-ryong.

There, Kim highlighted the alliance's readiness to counter North Korean threats.

"The South Korea-U.S. alliance would respond sternly to any North Korean provocations or aggression," Kim was quoted by his office as saying. "(We) would make North Korea clearly aware that should it attempt to launch a nuclear attack, its regime would be left with no scenario for survival anymore."

Kim also vowed to continue cooperating with the U.S. "systematically" to strengthen the credibility of America's extended deterrence, its stated commitment to mobilizing a full range of its military capabilities, including nuclear options, to defend its ally.

LaCamera stressed the "ironclad" U.S. security commitment to Seoul.

"The latest carrier striker group's visit to Korea and the ROK-U.S. combined naval exercise show U.S. determination and execution capability for extended deterrence and combat readiness," the commander was quoted by his office as saying. ROK stands for the South's official name, the Republic of Korea.

The arrival of the carrier, a centerpiece of America's naval might, came after Presidents Yoon Suk-yeol and Joe Biden reaffirmed their commitment to deploying U.S. strategic assets in a "timely and coordinated manner as necessary" during their summit in Seoul in May. (Yonhap)