The US and South Korean naval forces plan to stage four days of war games from Sunday off the tense Korean peninsula, days after the North launched a deadly artillery strike against the South.
Leading the show of firepower in the Yellow Sea will be nuclear-powered aircraft carrier the USS George Washington and its battle group, to be joined by a flotilla of South Korean destroyers and other warships.
The George Washington left its port in Japan on Wednesday, a day after North Korea stunned the world by launching a barrage of shells and rockets at a South Korean border island, killing two marines and two civilians.
China — which has refrained from criticising its traditional communist ally Pyongyang over the attack on the frontline island — has however put the United States on notice that it opposes the naval drill.
The Pentagon says the manoeuvre in international waters will be "defensive in nature", follows similar drills in the past, was planned months before North Korea's attack, and "is not directed at China".
The George Washington strike group conducted similar operations in October 2009 west of the Korean peninsula.
But Washington also says that its display of naval firepower will act as a "deterrent" to the volatile regime of Kim Jong-Il, which has kept the region on edge for years with its nuclear and long-range missile tests.
Yonhap news agency quoted an unnamed South Korean military source as saying: "The intensity of the exercise will be greater than had been planned. Participating forces will carry out firing and bombing drills."
Pyongyang claims it acted in retaliation Tuesday to a South Korean firing drill in what it regards as its own waters and has warned that the new war games mean the peninsula "is inching closer to the brink of war".
The centrepiece of the US Navy strike force is the 97,000-ton George Washington, which can carry about 75 aircraft on its 1.8 hectare (4.5 acre) flight deck and has a crew of 5,500 service personnel.
The George Washington and nine surface combatant ships together form the core of the Seventh Fleet, the US Navy's largest and only permanently forward deployed carrier strike group, based in Yokosuka near Tokyo.
Also taking part in the drill will be an embarked carrier air wing and vessels the USS Cowpens, Lassen, Stethem and Fitzgerald.
South Korea will deploy destroyers, patrol vessels, frigates, support ships and anti-submarine aircraft, the Joint Chiefs of Staff said without giving details of the numbers of ships or personnel, the Korea Times reported.
The US Forces Korea statement also said: "US and allied operations are built on an already strong foundation of cooperation and this exercise is intended to further enhance interoperability."