That tally has never been more critical, with the American government preparing to wind down evacuations as the U.S. military begins its final withdrawal from Afghanistan. On Tuesday, President Biden reaffirmed his plan to remove all American troops by Aug. 31, although he left room “to adjust the timeline should that become necessary.”

But U.S. officials believe that thousands of Americans remain in Afghanistan, including some far beyond Kabul, without a safe or fast way to get to the airport. Tens of thousands of Afghans who worked for the U.S. government over the last 20 years, and are eligible for special visas, are desperate to leave.

And refugee and resettlement experts estimate that at least 300,000 Afghans are in imminent danger of being targeted by the Taliban for associating with Americans and U.S. efforts to stabilize Afghanistan.