US Defense Secretary Robert Gates arrived in South Korea late Monday in a show of support for Washington's close ally, following high tensions with North Korea over the sinking of a warship.
Gates, who will be joined Wednesday by Secretary of State Hillary Clinton, was expected to announce dates for joint naval exercises designed to send a strong message of deterrence to the communist state.
South Korea and the United States, citing the findings of a multinational investigation, accuse the North of torpedoing a South Korean warship, the Cheonan, 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.
It says it was vindicated by a United Nations Security Council statement on July 9 which condemned the attack without specifying the culprit.
The United States, which stations 28,500 troops in the South, and South Korea are pressing ahead with the war games despite strong protests from the North's ally China.
The aircraft carrier USS George Washington and three destroyers are scheduled to arrive on Wednesday to take part.
But Seoul's defence ministry has said this month's drill has been relocated from the sensitive Yellow Sea to the Sea of Japan (East Sea) in deference to Chinese concerns.
It will however be just the first in a series of exercises this year, both sides have said.
Details will be announced on Tuesday, probably after Gates meets Defence Minister Kim Tae-Young, a defence ministry spokesman said.
The exercises will be "a show of force to the North Koreans... (sending) a very strong message of deterrence," said Pentagon spokesman Geoff Morrell last week.
Gates will meet Kim again Wednesday, while Clinton will hold talks with Foreign Minister Yu Myung-Hwan.
The "Two Plus Two" meeting, the first of its kind, was arranged to mark the 60th anniversary of the start of the Korean War, in which a US-led United Nations force defended the South.
The two sides plan a joint statement after the meeting. But the South is trying to ensure it omits mention of stalled six-party nuclear disarmament talks, according to Yonhap news agency.
After the UN statement, the North repeated its conditional willingness to return to the talks which group China, Japan, the two Koreas, Russia and the United States.
The South says the North is just trying to divert world attention from the sinking, and that its neighbour must show sincere willingness to disarm before the nuclear dialogue reopens.
"North Korea mentioned six-party talks after the UN Security Council statement but its sincerity is the key," foreign ministry spokesman Kim Young-Sun said Monday.
The South will note the stance of the North at the ASEAN Regional Forum on security issues in Hanoi Friday, Kim said.
The joint statement to be issued Wednesday will call for the North's denuclearisation but may not directly mention the six-party talks, Yonhap quoted one Seoul official as saying.
"We're in the middle of fine-tuning the wording of the statement," the official added.