An international investigation in May concluded that a North Korean submarine fired a torpedo that sank the Cheonan near the tense and disputed Korean sea border in late March.
Pyongyang flatly denies it was responsible and has warned any retaliation would trigger war.
The UN Command, which oversees an armistice that halted the Korean War in 1953, separately investigated if the sinking violated the truce, but the findings have not been disclosed.
Late last month, the command proposed military talks with North Korea to review its findings and initiate dialogue.
The North at first rejected the offer, criticising the US for trying to meddle in inter-Korean affairs under the name of the UN. But it reversed its position last week and proposed working-level talks at Panmunjom to prepare for higher-level talks by general officers on the sinking.
The UN Security Council approved a statement on Friday that condemned the sinking of the Cheonan, but stopped short of directly blaming North Korea.
The next day, the North said it would make efforts to resume stalled disarmament talks on its nuclear programme and conclude a peace treaty that could formally end the Korean War, a sign that the government could live with the council's presidential statement.
PJ Crowley, a spokesman for the US state department, said on Monday that North Korea must stop provocative actions and show a willingness to abide by past disarmament pledges before the US will agree to resume long-stalled six-nation talks meant to rid North Korea of its nuclear programme in return for aid.
"We are not willing to talk for the sake of talking," Crowley said.
The US stations 28,500 troops in South Korea, a legacy of the Korean War, which ended in an armistice that has never been replaced with a permanent peace treaty.