Update Dec. 12, 6:30pm EST: The Trump administration is reportedly planning to end protections that have allowed Vietnam War refugees to stay in the US for decades.

Those protections were part of a 2008 agreement between the US and Vietnam on how to return undocumented Vietnamese immigrants to their country. The deal states that it doesn’t apply to Vietnamese citizens who arrived in the US before 1995, when the two countries re-established diplomatic ties after the Vietnam War.

This is what the agreement says:

Vietnamese citizens are not subject to return to Vietnam under this Agreement if they arrived in the United States before July 12, 1995, the date on which diplomatic relations were re-established between the U.S. A 1111 Government and the Vietnamese Government.

For years, both American and Vietnamese officials had taken that to mean that the US wouldn’t deport pre-1995 arrivals. But US officials are now reinterpreting the scope of the agreement, as first reported by the the Atlantic. They say that although the deal does not provide for the US to deport pre-1995 arrivals, they can still be deported according to broader US immigration law.

“While the procedures associated with this specific agreement do not apply to Vietnamese citizens who arrived in the United States before July 12, 1995, it does not explicitly preclude the removal of pre-1995 cases,” a State department official told Quartz.

That controversial interpretation would make thousands of Vietnamese who have lived in the US for decades subject to deportation. The spokesman said discussions between the two countries about those immigrants are ongoing.

In response to questions from Quartz, a spokeswoman for the Department of Homeland Security focused on immigrants with criminal histories: “We have 5,000 convicted criminal aliens from Vietnam with final orders of removal,” she said. “These are non-citizens who during previous administrations were arrested, convicted and ultimately ordered removed by a federal immigration judge.”

However, she was not immediately available to clarify whether the new interpretation would also target law-abiding Vietnamese refugees.

This story was updated to include comments from the State Department.