HANOI, Vietnam — Thousands of Vietnamese living illegally in the United States now face deportation after the two countries completed an agreement Tuesday, a move that sparked worry among immigrant communities.

Vietnamese who entered the U.S. illegally after the former foes normalized relations in 1995 could now be forced to return to their birth country, said Julie Myers, director of U.S. Immigration and Customs Enforcement.

The deal has been under negotiation for 10 years. Vietnam had previously been reluctant to accept citizens back, and community leaders in the U.S. said many immigrants have been living with deportation orders for years, even decades.

"Some Vietnamese have been here a very long time," said Carolyn Tran, an organizer with VietUnity, an Oakland-based Vietnamese community organization. "They don't have a connection there any more."

Myers did not say how many Vietnamese are believed to be living illegally in the United States.

About 6,200 Vietnamese were given final deportation orders before the agreement's completion, and 1,500 more are involved in proceedings to eventually be sent home, she said during a visit to Vietnam.

The repatriation agreement provides steps for the U.S. to deport the Southeast Asian country's citizens who lack required documents, and for Vietnam to receive them.

"Vietnam has actually been a country that has been problematic for a long time, and this agreement we believe marks a new step toward making this process move more smoothly," Myers told The Associated Press.

More than 1.5 million overseas Vietnamese — the largest population outside Vietnam — live in the United States. Many fled their native country in boats after the Vietnam War ended in 1975 and northern communist forces took control of the former South Vietnam, which the U.S. had backed.

Critics of the agreement wonder whether this pact won't be rolled back to include others who entered the United States in the '70s and '80s.

"There is concern," said Joren Lyons, a staff attorney with the Asian Law Caucus in San Francisco, which has represented dozens of Vietnamese facing deportation orders. "Vietnam has said for decades no, these people can't be returned to Vietnam, and now they're saying yes. So is this a foot in the door? Will they start accepting people who came earlier as well?"