A US aircraft carrier arrived in South Korea on Friday for the first time in about four years, set to join other military vessels in a show of force intended to send a message to North Korea, officials said.
USS Ronald Reagan and ships from its accompanying strike group docked at a naval base in the southern port city of Busan.
Its arrival marks the most significant deployment yet under a new push to have more US "strategic assets" operate in the area to deter North Korea.
Strike group commander Rear Admiral Michael Donnelly told reporters aboard the ship that the visit had been long planned and was designed to build relations with South Korean allies and boost interoperability between the navies.
"We are leaving messaging to diplomats," he said, when asked about any signal to North Korea, but added that joint drills were designed to ensure the allies were able to respond to threats anywhere at any time.
"It's an opportunity for us to practice tactics and operations," Donnelly said.
South Korean President Yoon Suk-yeol has pushed for more joint exercises and other displays of military power as a warning to North Korea, which this year conducted a record number of missile tests after talks failed to persuade it to end its nuclear weapons and missile development.
Observers say Pyongyang also appears to be preparing to resume nuclear testing for the first time since 2017.
North Korea has denounced previous US military deployments and joint drills as rehearsals for war and proof of hostile policies by Washington and Seoul.
The visit is the first to South Korea by an American aircraft carrier since 2018. That year, the allies scaled back many of their joint military activities amid diplomatic efforts to engage with North Korea, but those talks have since stalled, and Pyongyang this month unveiled an updated law codifying its right to conduct first-use nuclear strikes to protect itself.
Questions have risen over the role the roughly 28,500 US troops stationed in South Korea might play if conflict erupts over Taiwan.
Donnelly said such questions are for policymakers above him, but said that operating with like-minded allies such as South Korea is a key part of the US Navy's efforts to maintain the regional security and stability that has existed for more than seven decades.
Officials declined to provide details of the upcoming joint drills, but said the carrier would be in port for "several days" while its crew visited Busan. Just hours after the ship docked, long lines of crewmembers formed as they took COVID-19 tests before being bused into the city.