President Barack Obama and the leader of Vietnam's Communist Party on Tuesday held what both called "candid" discussions on human rights during a historic White House meeting as the onetime enemies seek to bolster ties.
Nguyen Phu Trong is the first general secretary of the Vietnamese Communist Party to visit the United States and the White House, and was given the rare honor of an Oval Office welcome, usually reserved for heads of state and government.
The former foes -- which ended their bitter war 40 years ago, and are marking the 20th anniversary of the formal normalization of relations -- are seeking stronger ties in the face of an increasingly assertive China.
"Obviously there has been a difficult history," Obama told reporters in a brief joint appearance after their meeting. "What we've seen is the emergence of a constructive relationship that is based on mutual respect."
The US president said trade ties, tensions in the South China Sea over Beijing's territorial claims, and the thorny issue of human rights had been raised.
"We discussed candidly some of our differences around issues of human rights," Obama said, expressing confidence that any "tensions can be resolved in an effective fashion.
Trong described the talks as "cordial, constructive, positive and frank," and also qualified their talks on trade and rights as "candid."
"We have been transformed from former enemies to become friends, partners -- comprehensive partners," the party chief said.
"I'm convinced that our relationship will continue to grow in the future."
The White House talks -- followed by a lunch hosted by Vice President Joe Biden -- have certainly sparked criticism.
A few hundred protesters rallied outside the White House as Trong arrived, calling for expanded human rights in Vietnam -- an issue that has sparked concern among some American lawmakers about deepening ties.
Many demonstrators carried signs with slogans like "Freedom of speech in Vietnam now" and called on Hanoi to release all political prisoners.
In an open letter to the president, nine Democratic and Republican members of Congress have complained that the invitation and warm welcome for Trong send the wrong message.
"This authoritarian one-party system is the root cause of the deplorable human rights situation in Vietnam," the letter said, calling for Obama to demand the release of Vietnamese political prisoners.
Beyond the rights question, another major issue on the table is trade. Obama is seeking to reach a 12-nation Pacific trade pact, known as the Trans-Pacific Partnership, that would include Vietnam.
Republican Congressman Chris Smith, one of those who signed the letter, and others in Congress would like to see Vietnam excluded from the TPP until it makes progress on political rights.
"President Obama... still believes that trade will change Vietnam's behavior," Smith told AFP ahead of the visit.
"After Vietnam was given admission to the World Trade Organization in 2007, it ratcheted up repression; expecting a different result now is just plain unrealistic."
John Sifton, an Asia specialist for Human Rights Watch, said not much has changed in Vietnam to warrant an Oval Office sit-down.
"Vietnam remains a thoroughly autocratic and undemocratic state ruled by a single party, headed by Trong, in which repression, torture, and religious persecution are the norm," Sifton told AFP.
He called on Obama "to raise the volume on the human rights concerns -- especially so if the two countries are planning to announce a new level in their diplomatic ties."
Part of taking it to the next level could be the lifting of a US ban on weapons sales, which Vietnam is keen to achieve.
In October, Washington announced the partial lifting of the ban, and authorized sales of maritime defense equipment to Vietnam. But current US laws bar the sale of lethal weapons to Hanoi.
The State Department official said that Washington wanted to see more progress on human rights before going any further.
Trong was to meet with Senator John McCain, a onetime prisoner of war in Vietnam, on Wednesday, an aide to McCain said.