US President George W Bush says he is committed to drawing North Korea back to the negotiating table to defuse tensions over its nuclear programme.
Mr Bush said North Korea must heed incentives to end its isolation
Mr Bush said Pyongyang's withdrawal from talks had "strengthened the alliance" between the other nations involved in the negotiations.
He was speaking after meeting visiting South Korean leader, Roh Moo-hyun.
Pyongyang's exit from six-party talks last year and recent missile tests have sparked international concern.
The communist state tested seven missiles, including a new long-range weapon capable of hitting the US, on 5 July.
There has been speculation that North Korea may be planning what is thought to be its first nuclear test.
Appearing alongside Mr Roh at the White House on Thursday, Mr Bush said: "We reaffirmed our commitment to the six-party talks so that we can peacefully deal with the nuclear issue."
He said the five allies in the negotiating process - South Korea, the US, China, Russia and Japan - "were determined to solve this peacefully".
But he said, they recognised the "threat posed by a country in the region armed with a nuclear weapon".
Mr Bush said North Korean leader Kim Jong-il had to "understand that there is a better way to improve the livelihood of his people than be isolated".
Echoing Mr Bush, Mr Roh said: "We are working very hard for the resumption of the six-party talks."
South Korean media has recently suggested the US and Seoul differ on how to handle North Korea.
Pyongyang's neighbours should help it back to talks, the US says
Seoul is reportedly be seeking a softer approach towards Pyongyang, while the US is reportedly eyeing further economic sanctions.
A White House spokesman said the US believes North Korea's neighbours should lead the way in restoring dialogue.
Those closest to Pyongyang "have the most influence" and "need to step up" efforts to revive negotiations, the Associated Press news agency quotes the spokesman as saying.
North Korea has repeatedly asked for direct negotiations with the US, but Washington says all talks must take place within the multilateral framework.