Secretary of State Condoleezza Rice (search) was hunting for ways to end the yearlong impasse with North Korea over its nuclear weapons program as she embarked Friday on a trip to four nations in East Asia.

China may be the most difficult stop for Rice, given growing disagreements between the two countries on issues including North Korea (search). Rice will also visit Thailand, Japan and South Korea.

Administration officials have made clear they believe China is not doing enough to induce North Korea to return to the six-nation negotiating process over Pyongyang's nuclear arsenal. Since 2002, the United States has been seeking the verifiable dismantling of North Korea's nuclear weapons program in talks that also include China, South Korea, Japan and Russia.

Those discussions, held in 2003 and 2004, produced no visible progress and North Korea has declined to set a date for a new round. The administration is increasingly impatient with those talks, but there is no sign of any readiness to move to a different option.

On Friday, the Chinese government said it will send a special envoy to North Korea next week after Rice visits Beijing, the first stop in her Asian tour. The brief announcement did not say what message the envoy would carry to Pyongyang.

The Bush administration has discussed the possibility of taking the issue before the U.N. Security Council to increase pressure on North Korea. China has shown no interest in taking that step, or in using its economic leverage as the primary provider of energy and food aid to North Korea.

During a visit to New York last week, North Korea's director general of North American affairs, Li Gun, said the United States must withdraw its description of the communist nation as an "outpost of tyranny" and treat Pyongyang as a friend if it wants nuclear talks to resume.

North Korean complaints about Washington's rhetoric have been common.

In response to such concerns, the United States has been somewhat more respectful toward the North lately in its public comments and has repeated that it has no plans to attack the North.

At the last six-party meeting in June 2004, the United States said it was prepared to provide energy and other assistance to North Korea once the communist country provides convincing evidence that it is willing to dismantle its nuclear weapons program.

The administration says North Korea has not responded to the proposal.

After China, Rice's next stop will be Thailand, where she plans to examine reconstruction efforts in Phuket, which was devastated by the tsunami (search) last December.

Japan and South Korea will be her final stops. She visited those countries and China as well three months ago.