The United States and South Korea will launch a major military exercise on Sunday in the Sea of Japan as a warning to North Korea over the sinking of a South Korean ship, the two countries' defence chiefs said.
The drill is the first in a series designed "to send a clear message to North Korea that its aggressive behaviour must stop", US Defense Secretary Robert Gates and the South's Defence Minister Kim Tae-Young said in a joint statement on Tuesday after talks.
South Korea, the United States and other nations, citing findings of a multinational investigation, accuse the North of sending a submarine to torpedo the Cheonan warship near the tense Yellow Sea border in March.
The North denies involvement in the sinking, which claimed 46 lives, and says any retaliation could spark war.
The US-led United Nations Command said the drill from July 25-28 would involve about 20 ships including the 97,000-ton aircraft carrier USS George Washington and some 200 fixed-wing aircraft.
Although the two countries had staged large-scale military exercises in the past, this was the first in "many years" to be carried out in the aftermath of a "provocation" by North Korea, said Admiral Robert Willard, head of US Pacific Command.
Four F-22 Raptor fighter jets will also take part in this month's drill, flying training missions around Korea for the first time, Willard told a news conference.
"Our goal is to deter North Korea from future provocations," Willard said, adding it remained unclear if the drills would have the desired effect.
About 8,000 army, air force, navy and marine personnel from the two allies will take part, with drills covering anti-submarine warfare, mid-air refueling and cyber defence, officers said.
"We stand fully prepared to respond militarily to any further North Korean provocation," said General Han Min-Koo, chairman of South Korea's Joint Chiefs of Staff, in the UN Command statement.
Seoul's defence ministry said earlier the drill had been relocated from the sensitive Yellow Sea (West Sea) to the Sea of Japan (East Sea) in deference to Chinese protests.