Vietnam has been holding four Vietnamese-born American citizens since late November, accusing them of terrorism. The U.S. ambassador to Hanoi has criticized Vietnam's conduct in holding the U.S. citizens. Matt Steinglass reports for VOA from Hanoi.

Ambassador Michael Michalak says Vietnam has yet to announce any formal charges against the four U.S. citizens, and he disputed Vietnamese news accounts that accused them of involvement in terrorism.

"We see no information that would support charges of terrorism against these individuals that have been suggested by the local media," he said.

Two of the Americans, Quoc Quan Nguyen and Leon Trung, were arrested November 17 in Ho Chi Minh City, along with four other members of a U.S.-based Vietnamese exile group. The group, called the Viet Tan party, advocates multi-party democracy and an end to the Communist Party's exclusive rule in Vietnam.

Vietnam has long considered the Viet Tan party a terrorist organization, but Viet Tan officials says their methods are nonviolent. They say those arrested were discussing strategies for peaceful protests.

The other two Americans being held, Le Van Phan and Nguyen Thi Tin, were arrested November 23 at the Ho Chi Minh City airport, after a gun and ammunition were reportedly found in their baggage.

At a news conference, the ambassador revealed a wide gap in Vietnamese and U.S. attitudes towards the case, with the Vietnamese believing that the Viet Tan are linked to terrorism.

VIETNAMESE REPORTER: "So if one member of al-Qaida, for example, came to America with a fake passport, and break the border law, and he says he is just non-violent, how do the law enforcement authorities in the United States deal with this case?"

MICHALAK: "In the United States, as in Vietnam, I think it is article 72 of the Constitution, a person is not considered guilty until the courts have made up their mind."

The detention of the Vietnamese-Americans presents American diplomats with a dilemma. The United States enjoys increasingly warm relations with Vietnam, and has been seeking Vietnamese cooperation on counterterrorism and nuclear nonproliferation.

But Ambassador Michalak says the United States will not accept arrests of Americans, or Vietnamese, merely for peacefully voicing their political opinions.

"We have said that if they are detained for peaceful [activities], we will protest if they are detained for peaceful expression of political views," he said.

The ambassador would not specify what measures the United States might take in response.