Kerry says U.S. ties can grow if more freedom in Vietnam (Source: REUTERS). John Kerry: "Chúng ta tôn trọng quyền tự do ngôn luận của người dân nếu họ phát biểu ôn hòa"

U.S. Secretary of State John Kerry lauded on Friday the warming of ties with Vietnam but said the scope of relations, and military deals, would depend on its communist rulers' willingness to protect rights and freedoms.

Kerry is Vietnam's latest high-profile visitor from Washington as the former enemies mark two decades of calibrated engagement since the normalization of ties that have expanded rapidly in the past year.

In a speech to mark the anniversary, Kerry said barriers of "mistrust and misunderstanding" were falling and urged Vietnam to show greater commitment to pursuing legal reforms and allowing freedom of expression and assembly.

"Progress on human rights and the rule of law will provide the foundation for a deeper and more sustainable strategic partnership," Kerry said.

"Only you can decide the pace and direction of the process."

Despite pursuing Western engagement and economic reforms, Vietnam has been chided for crushing dissent, with bloggers, activists and journalists among those facing harassment, arrest and jail.

The United States has been courting Vietnam to boost its influence in Asia and offset China's, but human rights and political prisoners have been a sticking point.

Washington cited some progress last year and started easing its lethal arms embargo on Vietnam, allowing for defence engagement and joint military drills.

Kerry said the message was that a further easing of the embargo hinged on rights.

"Is there room for further improvement? Yes," Kerry told a news conference with Vietnam's deputy prime minister and foreign minister, Pham Binh Minh.

"We will continue to urge Vietnam to reform certain laws that may have been used to arrest ... somebody for expressing a peaceful point of view.

"With respect to the lethal weapons, any further steps obviously will be tied to political progress."

Minh said promoting rights was a priority and legal reforms were being implemented. He said rights in Vietnam had "special character" in the local context, but his country was open to discuss differences to improve.

Kerry urged Vietnam to recognise free speech and assembly, which millions of its people were exercising on Facebook and through workers defending their rights.

"There are basic principles we will defend: No one should be punished for speaking their mind so long as they are peaceful," he said in his earlier speech.

He also met President Truong Tan Sang, who recognised the importance of guaranteeing human rights, he said.

"He couldn't have been more clear about how important it is (to Vietnam's leaders) to respect the rights of their people," Kerry