President Bush, speaking after an historic meeting with Vietnamese Prime Minister Phan Van Khai at the White House today, announced he will visit Vietnam in 2006 on the invitation of the communist leader.

Bush also said he backs Vietnam's bid to join the World Trade Organization, an important U.S. announcement for Hanoi. Getting Washington's support for WTO membership was one of Khai's key goals for his U.S. visit.

The symbolic White House meeting, scheduled to mark the 10th anniversary of normalized relations between the United States and Vietnam, marked the first trip to the United States by a Vietnamese Communist leader. Khai, 71, said the visit showed Vietnam and the United States, once bitter enemies, had "entered a new stage of development."

As the two leaders met, scores of protesters, mostly Vietnamese and Vietnamese-Americans, demonstrated across the street from the White House, calling for religious freedom and respect for human rights in the Southeast Asian country. The protesters chanted "VC (Viet Cong) go home" and "No money for Communists."

Bush called the meeting a "constructive visit" during which the two leaders discussed a wide range of subjects, including Vietnam's willingness to continue looking for the remains of Americans killed during the Vietnam War and security issues related to counter-terrorism efforts. He said the two also discussed Vietnam's WTO bid, the country's progress on the fight against HIV/AIDS and the healthy growth of the Vietnamese economy.

On the eve of his trip, Khai said in an interview with The Washington Post that Vietnam and the United States will now cooperate in the exchange of intelligence on terrorism and transnational crime. Analysts said Khai's U.S. trip is a milestone, a signal that a mature relationship based on mutual interests in security and trade is starting to take shape.

Since the United States and Vietnam restored diplomatic ties a decade ago, trade between the two former combatants has risen steadily, reaching $6.4 billion in 2004. The United States is now Vietnam's biggest trading partner.

After the meeting, Bush said that the two countries had also signed a "landmark agreement that will make it easier for people to worship freely in Vietnam." No details about the agreement were immediately released. Bush and Khai had been expected to address U.S. concerns about human rights and religious freedom in Vietnam. But no further mention of the concerns were made.

Khai said he and Bush agreed that "there remain differences between our two countries due to the different conditions that we have, the different histories and cultures, but we also agreed that we should work together through a constructive dialogue based upon mutual respect to reduce those difficulties."

About his upcoming Vietnam trip, Bush said: "The Prime Minister graciously invited me to Vietnam. I will be going in 2006. I'm looking forward to my trip." Bush's visit will coincide with the Asia-Pacific Economic Cooperation summit in Hanoi in late 2006, which Vietnam is hosting. Former President Bill Clinton visited Vietnam in 2000, the first visit by an American president to Vietnam since the war.

Khai, an economic modernizer, is on a week-long visit to the United States, during which he will meet with business leaders on both coasts. He will be ringing the opening bell on the New York Stock Exchange later this week, a symbol of Vietnam's recent economic progress.

He was also meeting with Defense Secretary Donald H. Rumsfeld on Tuesday.

Khai arrived in the United States on Sunday and visited Boeing Co.'s plant south of Seattle to check on the purchase of four Boeing airliners by Vietnam Airlines. On Monday, he met with Microsoft Corp. Chairman Bill Gates at the company's headquarters in Redmond, Wash.

In Seattle, Khai was greeted by demonstrators shouting "Down with Communists" and calling for an end to political and religious persecution in the country. The U.S.-based Human Rights Watch says it has documented cases of human rights abuses by Vietnam's communist government, including the arrests of dissidents promoting human rights.

Khai's trip is part of a wider effort by Vietnam to establish stronger relations globally, and analysts say the trip's success is crucial if economic reforms are to continue to flourish.

Khai was a member of Vietnam's revolutionary youth group in 1947, served as a government planner during the Vietnam War and was chosen prime minister by the country's Communist-governed National Assembly in 1997.

Washington Post staff writer Ellen Nakashima contributed to this report