HANOI, Vietnam -- President Bush, trying to stiffen global resolve to confront North Korea, failed to win South Korea's support today for a tough inspection program to intercept ships suspected of carrying supplies for Pyongyang's nuclear weapons and missiles.

Mr. Bush sought to persuade South Korean President Roh Moo-hyun to fully implement U.N. sanctions imposed on North Korea for testing nuclear weapons. He also sought South Korea's support in the Proliferation Security Initiative, or PSI, a voluntary international program that calls for stopping ships suspected of trafficking in weapons of mass destruction.

Mr. Roh said his country "is not taking part in the full scope" of the security initiative, but that it would "support the principles and goals of the PSI."

Mr. Bush met with Mr. Roh before the opening of a summit of 21 Pacific Rim leaders. The president tried to put the best face on the disagreement, saying he and Mr. Roh have a mutual desire to "effectively enforce the will of the world" through U.N. sanctions imposed on North Korea for its nuclear test.

"I appreciate the cooperation we're receiving from South Korea for the Proliferation Security Initiative," Mr. Bush said. "Our desire is to solve the North Korean issue peacefully," he said, adding that the United States and South Korea were "allies in peace."

North Korea is a primary target of the Proliferation Security Initiative. South Korea has only been an observer to the program out of concern that its direct participation in stopping and searching North Korean ships could lead to armed clashes with its volatile neighbor.

The White House acknowledged that Mr. Roh faced political pressure back home not to anger North Korea. Mr. Bush "understands political constraints," said White House press secretary Tony Snow. "We just had an election" in which Mr. Bush's Republican Party lost control of Congress for the first time in 12 years.

Mr. Snow said South Korea promised support for the PSI program, but he offered no details of Seoul's cooperation.

Mr. Bush was the second U.S. president, after Bill Clinton, to visit Vietnam since the war ended three decades ago with U.S. defeat. In Hanoi, powerful reminders remain of the fighting three decades ago, the longest U.S. war and one that -- like Iraq -- bitterly divided Americans.

Asked if the experience in Vietnam offered lessons for Iraq, Mr. Bush said, "We tend to want there to be instant success in the world, and the task in Iraq is going to take awhile."

He said "it's just going to take a long period of time" for "an ideology of freedom to overcome an ideology of hate. Yet, the world that we live in today is one where they want things to happen immediately. ... We'll succeed unless we quit," the president said.

His talk about impatience brought a rejoinder back home from Sen. Dick Durbin of Illinois, who will be the new Senate's second-ranking Democrat. "I think we ought to show a little impatience when it comes to the Iraqis and their unwillingness to respond to the need to change," Mr. Durbin said at a St. Louis news conference. "America has been patient. Our troops have been heroic. ... It is time for the Iraqis to stand up and defend their own country.

In weekend discussions, Mr. Bush hoped to coordinate strategy with China, Russia, Japan and South Korea for the resumption of disarmament negotiations with North Korea. Mr. Bush was to see Japan's new prime minister, Shinzo Abe, later today.

In all, leaders of 21 nations and territories are gathered in Hanoi, and it is unclear whether the summit will produce a unified stand toward North Korea.

As for local Vietnamese, the turnout for Mr. Bush as his motorcade moved past storefronts was far more subdued that the enthusiastic reception that greeted then-President Clinton exactly six years ago. A few people waved, but most merely watched impassively. Weary of war, many deeply disapprove of the U.S.-led invasion of Iraq.

Mr. Bush's limousine took him along Truc Bach Lake, where then-Lt. Cmdr. John McCain, now an Arizona Republican senator, was captured after parachuting from his damaged warplane. Mr. McCain spent more than five years as a prisoner of war.

"He suffered a lot as a result of his imprisonment, and yet we passed the place where he was literally saved, in one way, by the people pulling him out," Mr. Bush said. He was speaking with reporters after meeting with Australia's Prime Minister John Howard, a staunch partner in Iraq.

Mr. Bush was to pay a visit today to the Joint POW/MIA Accounting Command, charged with recovering and identifying the remains of Americans who were killed in action but never brought home. With personnel in Vietnam, Laos, Thailand and Hawaii, the command identifies about six MIAs each month.

Reflecting on his visit, Mr. Bush said, "My first reaction is history has a long march to it, and that societies change and relationships can constantly be altered to the good."

There were bronze busts of Ho Chi Minh, the victorious North's revolutionary communist leader, as Mr. Bush met with the Vietnamese president, the prime minister and the Communist Party general secretary. But there also were signs of change and of Vietnam's quest to replace poverty with prosperity.

Nong Duc Manh, the Vietnamese Communist Party general secretary, was quoted by the White House as telling Mr. Bush that his country wanted to "put aside the past and look forward to the future."

Facing resistance in Congress, Mr. Bush was unable to deliver promised normalized trade benefits to Vietnam, but said he was confident that those provisions would eventually win approval.