U.S. Defense Secretary Donald Rumsfeld has met with senior communist officials in Vietnam during a visit aimed at boosting military ties with the former enemy. The visit is part of a tour of several Asian nations during which terrorism and regional security are also under discussion.

Defense Secretary Donald Rumsfeld, left, shakes hands with Vietnamese Prime Minister Phan Van Khai

U.S. Defense Secretary Donald Rumsfeld and Vietnam's Defense Minister Pham Van Tra have agreed to increase efforts to recover soldiers from both sides missing-in-action during the Vietnam War. The two governments are also to boost joint medical training programs and military visits.

Rumsfeld told reporters Sunday that the aim is to gradually improve relations, which still bear scars from the Vietnam War more than three decades ago.

"What we want to see is a relationship between our country and Vietnam evolve in a way that is comfortable to them and is comfortable to us," he said, "And it has been doing that over recent years, and I suspect it will continue along that path."

It was the second visit to Vietnam by a U.S. defense chief since diplomatic relations were restored 11 years ago, some 20 years after the defeat of the U.S. backed government in the former South Vietnam by the communist government in North Vietnam.

Relations initially were mutually suspicious but warmed slowly through military visits and cooperation in the search for the thousands of American and Vietnamese soldiers missing-in-action during the war.

Growing economic ties have further boosted relations, with trade now surpassing $6 billion per year. And the two governments last week signed a bilateral trade agreement that paves the way for Vietnam to join the World Trade Organization (WTO) by the end of the year.

Rumsfeld has visited Vietnam twice in the past, first as a member of congress and later as a private businessman. On Sunday, he praised Vietnam's economic dynamism.

"I've been impressed with the Vietnamese people, with their economy," he said. "They have got a very good growth rate. They have a sizable population and they're industrious and I think it would be a very good thing to have them in the WTO."

The American defense chief earlier visited Singapore where he urged China to be more open about the purpose of its rising military budget.

Rumsfeld is to visit Indonesia Tuesday for meetings that are expected to focus on terrorism. Indonesia has arrested 200 alleged Islamic militants in recent years but Indonesian officials have warned the U.S. government that forcing its views about how to fight terrorism on other nations could result in a loss of sympathy for the cause.