North Korea has told the US it will honour its pledge to reveal all the details of its nuclear programme, a White House official has said.
North Korea is in the process of disabling its Yongbyon reactor
Pyongyang said it would keep to its side of a disarmament-for-aid deal and expected Washington to do the same.
North Korea was responding to a personal letter to leader Kim Jong-il from President Bush earlier this month.
The official said the response was delivered verbally through North Korea's delegation in New York.
"We'll live up to our side and hope you'll live up to your side," the official, who spoke to reporters on condition of anonymity, paraphrased Pyongyang's response.
However, it remained unclear if the message was directly from North Korean leader Kim Jong-il.
President Bush's letter to Mr Kim was thought to be his first direct communication with the leadership of North Korea - the country Mr Bush once described as being part of "an axis of evil".
Mr Bush's letter was delivered by US envoy Christopher Hill during his talks with North Korea's Foreign Minister Pak Ui-chun on 4 December.
In the letter, Mr Bush "stressed the need for North Korea to come forward with a full and complete declaration of their nuclear programmes," US National Security Council spokesman Gordon Johndroe said last week.
Mr Johndroe added that President Bush had also written to all leaders involved in the six-party talks about North Korea's nuclear programme.
Under the deal, signed in February, Pyongyang pledged to declare all its nuclear programmes and disable Yongbyon by the end of the year.
In return, Washington agreed to begin normalising relations with Pyongyang and remove the country from its state sponsors of terrorism and trade sanctions blacklists.