WATCH: Jen Psaki holds White House news briefing

White House press secretary Jen Psaki held a news briefing Tuesday as President Joe Biden adheres to an Aug. 31 deadline to withdraw U.S. troops from Afghanistan.

Watch the briefing in the video player above.

Psaki said Biden, whose handling of the hastily arranged evacuation has been roundly criticized by Republicans and Democrats alike, announced during a meeting of fellow leaders of the G-7 industrialized nations that he planned to stick to the Aug. 31 deadline. British, French and other officials argued for extending the deadline, officials said.

Biden was to speak publicly late Tuesday.

“He also made clear that with each day of operations on the ground, we have added risk to our troops with increasing threats from ISIS-K, and that completion of the mission by Aug. 31 depends on continued coordination with the Taliban, including continued access for evacuees to the airport,” Psaki said. ISIS-K is the Islamic State affiliate in Afghanistan, which Biden has vowed to keep in check even after U.S. forces leave.

Psaki said Biden has asked the Pentagon and the State Department for evacuation contingency plans to “adjust the timeline should that become necessary.”

At the Pentagon, spokesman John Kirby said Aug. 31 leaves enough time to get all Americans out, but he was less specific about completing the evacuation of all at-risk Afghans. He said about 4,000 American passport holders and their family members had been evacuated from Kabul as of Tuesday.

“We expect that number to grow in coming days,” Kirby said. He also said the military would have to start moving troops and their equipment out of Kabul several days prior to Aug. 31 in order to be out entirely by then.