SEOUL - North Korea said on Sunday it was ready to sink a US aircraft carrier to demonstrate its military might, as two Japanese navy ships joined a US carrier group for exercises in the western Pacific.
US President Donald Trump ordered the USS Carl Vinson carrier strike group to sail to waters off the Korean peninsula in response to rising tension over the North's nuclear and missile tests, and its threats to attack the United States and its Asian allies.
As the Vinson sailed in waters around Korea Sunday, it was joined for an at-sea military exercise by two Japanese destroyers, the Samidare and Ashigara.
The Japanese ships were making a show of solidarity as the United States confronts North Korea over its ballistic missile programme and nuclear tests.
The destroyers will "practice a variety of tactics" with the US strike group, the Japan Maritime Self Defence Force (MSDF) said in a statement.
North Korea remained defiant.
"Our revolutionary forces are combat-ready to sink a US nuclear powered aircraft carrier with a single strike," the Rodong Sinmun, the newspaper of the North's ruling Workers' Party, said in a commentary.
The paper likened the aircraft carrier to a "gross animal" and said a strike on it would be "an actual example to show our military's force".
The commentary was carried on page three of the newspaper, after a two-page feature about leader Kim Jong Un inspecting a pig farm.
In a separate development North Korea detained a US citizen on Friday, South Korea's Yonhap news agency reported, bringing the total number of Americans held by the isolated country to three.
The man, a Korean-American in his fifties identified only by his surname Kim, had been in North Korea for a month to discuss relief activities, Yonhap said on Sunday. He was arrested at Pyongyang International Airport on his way out of the country.
The man was a former professor at Yanbian University of Science and Technology (YUST), Yonhap said, citing unnamed sources. YUST, a university in neighbouring China, has a sister university in Pyongyang.
North Korea was already holding two Americans.
Otto Warmbier, a 22-year-old student, was detained in January last year and sentenced to 15 years of hard labour by a North Korean court for attempting to steal a propaganda banner.
In March 2016, Korean-American Kim Dong Chul, 62, was sentenced to 10 years hard labour for subversion.
US missionary Kenneth Bae was arrested in 2012 and sentenced to 15 years hard labour for crimes against the state.
He was released two years later.
North Korea will mark the 85th anniversary of the foundation of its Korean People's Army on Tuesday.
It has in the past marked important anniversaries with tests of its weapons.
North Korea has conducted five nuclear tests, two of them last year, and is working to develop nuclear-tipped missiles that can reach the United States.
It has also carried out a series of ballistic missile tests in defiance of United Nations sanctions.
North Korea's growing nuclear and missile threat is perhaps the most serious security challenge confronting Trump.
He has vowed to prevent the North from being able to hit the United States with a nuclear missile and has said all options are on the table, including a military strike.