U.S. Homeland Security officials have begun "extreme vetting" interviews at Australia's offshore detention centers, two sources at the camps said Tuesday, as Washington honors a refugee swap U.S. President Donald Trump had called "a dumb deal."

The Trump administration said last month the agreement to offer refuge to up to 1,250 asylum seekers in the centers would progress on condition that refugees satisfied strict checks.

In exchange, Australia has pledged to take Central American refugees from a center in Costa Rica, where the United States has expanded intake in recent years, under the deal struck with former President Barack Obama.