US Secretary of State John Kerry met Vietnamese President Truong Tan Sang and other prominent Communist party leaders in Hanoi Friday and hailed the former foes' transformation from enemies to key allies in the two decades since ties were established betwen the two countries.

"In 20 years we have traveled a remarkable distance," Kerry said, hailing bilateral cooperation in fields ranging from education to regional security.

"The journey of reconciliation between our countries is really one of the great stories of nations that once were at war being able to find common ground and create a new relationship," he added.

Kerry, a Vietnam War veteran, said the conflict was the result of a "most profound failure of diplomatic insight and political vision."

He lamented that current discussions have often focused on the alleged necessity of conflict.

"There are times when one may have no choice but to go to war, but it is never something to rush to or accept without exploring every other available option," he said.

Upholding human rights 'will serve Vietnam's interests'

Kerry, who is on the last leg of a five-nation tour of the Middle East and Southeast Asia, said barriers of "mistrust and misunderstanding" were falling.

But he also urged Vietnam to show greater commitment to pursuing legal reforms and allowing freedom of expression and assembly.

Kerry said the United States respected the different political systems of both countries but said it was important for stability to formally recognize free speech and assembly, which millions of Vietnamese were already demonstrating with Facebook and through workers defending their rights.

Despite seeking deeper Western engagement and reform to its economy, Vietnam's government has been criticized for its zero-tolerance approach to dissent, with bloggers, religious activists and journalists among those facing harassment and arrest, or languishing in jail.

"There are basic principles [the United States] will defend: no one should be punished for speaking their mind so long as they are peaceful; and if trading goods flow freely between us, so should information and ideas," Kerry said. "And we believe that progress in upholding these basic human rights will absolutely serve Vietnam's interests."

If Vietnam expects to benefit from the protections of international rules and regulations it must also uphold international standards, Kerry said.

Ties with Vietnam vital for US Asia policy

Despite the rights concerns, US officials see stronger ties with Vietnam as a linchpin in President Barack Obama's Asia policy.

Kerry encouraged Vietnam to adopt a Pacific Rim trade pact that is currently being negotiated and he reiterated the US commitment to helping the country protect and patrol its territorial waters.

Vietnam is among the Southeast Asian nations with competing claims with China over areas of the South China Sea, and has sought US support for negotiated resolutions to the disputes.

mh/sms (AFP, AP, Reuters)