President Joe Biden’s administration assessed “thousands” of lawful permanent residents of the United States remain in Afghanistan following the tumultuous evacuation of Kabul, according to Secretary of State Antony Blinken. “I think the best estimates are that there’s several thousand green card holders in Afghanistan,” Blinken told the House Foreign Affairs Committee on Monday. That figure hints at the scale of the diplomatic and humanitarian challenge confronting State Department officials in the absence of U.S. military personnel. Blinken’s team is developing new plans for securing the departure of the remaining American citizens, green card holders, and Afghan allies expected to face retaliation from the Taliban for their past work with the U.S. government — but the number of Afghans eligible for Special Immigrant Visas remains unclear. “Those are numbers that we’re working on right now as people come out of Afghanistan — some of them in the United States already, others at these transit points — we’re collecting all of that information,” Blinken testified. The days since the end of the U.S.-led evacuation have been marked by confusion and anxiety for Americans and Afghans still in Afghanistan. Taliban officials allowed Qatar Airways to begin flying charter flights out of Kabul’s international airport last week, but that operation was put on hold Friday and “will remain paused for at least seven additional days,” according to a White House official, due to a reported measles outbreak. Meanwhile, an array of charter flights at an airport in Mazar-i-Sharif remain grounded. Blinken has faulted the Taliban for refusing to allow the flights to depart, but U.S. officials also concede the flights have been stalled due to the difficulty of verifying identities and their eligibility for entry to the U.S.