Hanoi - The United States "would like to increase military- to-military relations" with its former adversary Vietnam, said US Senator and former presidential candidate John McCain at a press conference in Hanoi Tuesday.

McCain, a former Navy fighter pilot who spent five years as a prisoner of war (POW) in Hanoi during the Vietnam War, said such ties might include the training of Vietnamese officers at US defence institutions.

Addressing students at Vietnam's Diplomatic Academy earlier in the day, McCain placed such US-Vietnamese military cooperation in the context of recent Chinese harassment of a US naval vessel in the South China Sea. He also noted China's disputes with Vietnam and other countries over the Spratly and Paracel Islands.

McCain is visiting Vietnam as part of a tour of East Asia along with two other US senators, Republican party politician Lindsey Graham (also a Vietnam veteran) and Democrat Amy Klobuchar. The group first visited Japan, and will travel to Beijing Wednesday.

In other remarks at the Diplomatic Academy, McCain said Vietnam should liberalize its political system in order to compete with China.

"By taking steps toward greater political liberalization, Vietnam has the chance not simply to match (China's) accomplishments but to surpass them," McCain said.

On Wednesday, McCain plans to visit Hoa Lo Prison, known to former US prisoners of war as the "Hanoi Hilton," where he was held for several years after he was shot down on a bombing mission over Hanoi in 1967.

Like dozens of other former POWs, McCain has said he was tortured by his captors to compel him to record anti-American propaganda statements. The Vietnamese government maintains it never mistreated any prisoners.

McCain went on to play a crucial role in reestablishing diplomatic relations between the US and Vietnam in the early 1990s.

Also at the press conference, Graham called on Vietnam to "take a strong stand" against North Korea's missile program.

Vietnam is a non-permanent member of the UN Security Council, where the US pushed for sanctions on North Korea after it conducted a prohibited missile launch Sunday. After the launch, the Vietnamese government called for a "restrained response."(dpa)