Refugees who were slated to travel to the United States after a years-long and often cumbersome process have had their flights canceled, according to a State Department memo to resettlement partners obtained by CNN.

The surprise halt of travel this week scuttled the hopes of last-minute arrivals as Donald Trump's refugee shutdown took hold early.

The fate of tens of thousands of Afghans awaiting resettlement in the U.S. hangs in the balance after Trump suspended the refugee admissions program.