WASHINGTON (AFP) - President Barack Obama will receive the head of Vietnam's Communist Party Tuesday in the Oval Office, in an extraordinary meeting for an unelected leader in the single-party country that has alarmed some American lawmakers.
Just after the 40-year anniversary of the fall of Saigon during the Vietnam War and 20 years after the restoration of diplomatic ties between the former enemies, Obama will host Nguyen Phu Trong, General Secretary of the Communist Party.
Trong will become the first General Secretary of the Vietnamese Communist Party to visit the United States and the White House.
Former President Bill Clinton normalised relations with Vietnam and made a historic visit to the country in 2000.
Obama's administration, which has increasingly put its foreign policy focus on Asia, has a clear commitment to strengthening ties with Hanoi.
Vietnam, meanwhile, is eager to develop its economic and military ties with the United States, particularly at a time when China has been more willing to project its power around its borders.
But the visit by Trong has also stirred criticism.
In an open letter to the president, a number of members of Congress from both the Democratic and Republican parties complain that Trong's invitation sends the wrong message because of Vietnam's human rights record.
He was invited without being an head of state or representative of an elected government, the lawmakers point out.
"This authoritarian one-party system is the root cause of the deplorable human rights situation in Vietnam," their letter said, calling for Obama to demand the release of political prisoners in Vietnam.
"It's not a classic encounter for the president," said a senior US official, stressing that the Trong is one of the most powerful people in the country and the meeting is important to strengthen ties with Hanoi.
John Sifton, an Asia specialist for Human Rights Watch, doesn't think much has changed in Vietnam to warrant an Oval Office sit-down.
Sifton says Obama has raised the issue of political prisoners in Vietnam several times, "the problem is that the messages are not getting through."
"President Obama should not be meeting with Secretary General Trong... But if he must, he needs 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," he said.
The question of the US arms embargo on Vietnam is likely to be discussed in the meeting Tuesday.
In October, Washington announced the partial lifting of the ban, and authorized sales of maritime defense equipment to Vietnam.
Other weapons shipments remain prohibited.
A senior State Department official said the Vietnamese have been told that their human rights situation would be monitored closely before any decisions on the arms embargo.
The Trans-Pacific Partnership trade agreement that Obama is looking to finish also is expected to be on Tuesday's agenda.