"During a meeting this morning with the G7 leaders, the President conveyed that our mission in Kabul will end based on the achievement of our objectives," White House Press Secretary Jen Psaki said in a statement Tuesday.

Psaki added that the current evacuation effort is "on pace to finish by August 31st," but also warned that troops on the ground face "increasing threats from ISIS-K" as the mission evolves.

"[C]ompletion of the mission by August 31st depends on continued coordination with the Taliban, including continued access for evacuees to the airport," Psaki said. "In addition, the President has asked the Pentagon and the State Department for contingency plans to adjust the timeline should that become necessary."

Psaki did not clarify when exactly the August 31 deadline would go into effect. In a news conference on Tuesday, a reporter asked her whether the deadline would go into effect at midnight on August 31 U.S. Eastern time or Afghanistan time. "That's really a great question," Psaki said. She pledged to "get back to you on that."

Psaki also confirmed that the evacuations will stop before August 31 in order to allow the military to withdraw to meet the deadline.