With logistics and conditions at the Kabul international airport growing more dire, the Biden administration on Tuesday is scheduled to discuss with allies a withdrawal from Afghanistan beyond an Aug. 31 deadline that left just eight days to evacuate thousands of people.

Compounding the problem are the challenges borne of the more rapid than expected Taliban takeover. The State Department doesn’t know exactly how many Americans are left on the ground, although some have estimated that between 10,000 and 15,000 were there when the evacuations began, several U.S. officials said…

Mr. Biden’s national security adviser, Jake Sullivan, said Monday that the number of Americans on the ground is hard to assess because many Americans didn’t register with the embassy when they arrived in Afghanistan, and many didn’t deregister when they left. “Now, it’s our responsibility to find them,” Mr. Sullivan said.