US President Joe Biden arrives in Vietnam on Sunday set to deepen cooperation between the two nations, in the face of China's growing ambitions in the region.

Biden — who is flying from the G20 summit in New Delhi — will meet the leader of Vietnam's ruling Communist Party, Nguyen Phu Trong, on Sunday, and is expected to sign off on a "comprehensive strategic partnership", Hanoi's highest level of diplomatic ties.

The underlying goal of the short visit will be much the same as during Biden's time at the G20 gathering — to shore up support against China's increasing influence.

For Vietnam, the upgrading of diplomatic ties is significant. It only has top-level ties with Russia, India, South Korea and China.

Although it will be careful to be seen as not taking sides between the United States and China, Vietnam shares American concerns about its neighbor's growing assertiveness in the contested South China Sea.

The United States and Vietnam — a key manufacturing hub — also have increasingly close trade ties, and Washington sees Hanoi as an important partner as it looks to source less from China after supply chain shocks rocked the global economy in recent years.

In Hanoi on Sunday, there will be a welcome ceremony, speeches by the two leaders and a press conference by the US president — who on Tuesday awarded the top US military honor to a helicopter pilot who rescued four soldiers during the Vietnam War.

Biden will meet President Vo Van Thuong and Prime Minister Pham Minh Chinh the following day.

Ahead of the 80-year-old US president's arrival, Hanoi's central Hoan Kiem Lake area, packed with families out for a weekend stroll, was adorned with American and Vietnamese flags.

Nearby in the city's old quarter, a souvenir shop sold T-shirts with Biden's face emblazoned across the front.

"I think the US is a good friend to Vietnam," said the shop's 61-year-old owner Truong Thanh Duc.

"With this visit of President Joe Biden, I think he will bring more business contracts and jobs to Vietnamese people."

– Human rights –
In Vietnam, Biden will be juggling strategic interests with the defense of human rights.

The Southeast Asian country has a dire human rights record. Government critics face intimidation, harassment and imprisonment after unfair trials, and there are reports of police torture to extract confessions, Human Rights Watch says.

While the president has often criticized China's human rights record, he has largely stayed quiet on Vietnam and campaigners are fearful he may not press the subject.

National Security Advisor Jake Sullivan said prior to the trip that Biden would raise issues related "to freedom of expression, freedom of religion, and other basic human rights".

His visit comes days after a US government commission on religious freedom harshly criticized Vietnam for "egregious, ongoing, and systematic violations".

On Saturday, Nguyen Bac Truyen, a legal expert and religious freedom advocate who was sentenced in 2018 to 11 years in prison for subversion, said on Facebook he had been released and allowed to travel to Germany with his wife.

Vietnam often releases political prisoners prior to US presidential visits.

Biden's visit to Hanoi will mean he leaves early from the G20 summit, where leaders agreed on a joint declaration that papered over deep divisions on the war in Ukraine and tackling climate change, avoiding direct criticism of Moscow and any concrete pledge to phase out polluting fossil fuels.

His Vietnam trip will also include a poignant visit to the memorial to his friend John McCain, the former US senator shot down and held captive during the Vietnam War who in later years helped rebuild ties between the two countries.

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© Agence France-Presse