Updated

President Biden said Tuesday that the U.S.'s planned troop withdrawal from Afghanistan on Aug. 31 was contingent on the Taliban's continued cooperation with ongoing efforts to evacuate thousands of Americans and Afghan allies from Kabul's airport.

Biden's speech from the White House came shortly after his meeting with leaders from the G-7, the United Nations, NATO and the European Union. The president said U.S. forces and their allies were "currently on a pace to finish" evacuations by his original deadline, adding that any delays would exacerbate the risk of a terrorist attack on the airport.

"The sooner we can finish, the better," Biden said. "Each day of operations brings added risk to our troops."

"The completion by Aug. 31 depends on the Taliban continuing to cooperate and allow access to the airport to those who are transporting out and no disruptions to our operations," he added. "In addition, I’ve asked the Pentagon and the State Department for contingency plans to adjust the timetable should that become necessary. I’m determined to assure that we complete our mission, this mission."

Biden's remarks echoed details included in a statement earlier Tuesday from White House Press Secretary Jen Psaki. The news comes shortly after U.S. officials told Fox News that some of the 6,000 troops in Kabul were leaving.

A U.S. official stressed to Fox News, "We can still defend the airport."

Defense Dept. Press Secretary John Kirby stressed, "commanders on the ground are empowered to make any adjustments they see fit, when they see fit. That includes changes to the footprint. To that end, we can confirm reports of the departure from Afghanistan of several hundred U.S. troops. These troops represent a mix of headquarters staff, maintenance and other enabling functions that were scheduled to leave and whose mission at the airport was complete. Their departure represents prudent and efficient force management. It will have no impact on the mission at hand."

BIDEN ADMIN DOUBLES DOWN ON PSAKI CLAIM AMERICANS NOT STRANDED IN AFGHANISTAN

U.S. officials told Fox News earlier Tuesday that Biden decided not to extend an Aug. 31 deadline to remove all American troops from Afghanistan. Biden's move to maintain his original deadline drew bipartisan criticism from lawmakers amid concerns that some Americans and Afghan allies could be left behind.

A Taliban spokesperson – following a meeting between leader Mullah Abdul Ghani Baradar and CIA Director William Burns in Kabul – said there will be "no extensions" to the Aug. 31 date.  

Kirby also said Tuesday that the number of U.S. troops in Afghanistan will go to "zero" at the Aug. 31 deadline. 

"We continue to make progress every day in getting Americans – as well as Special Immigrant Visa applicants and vulnerable Afghans – out," he said. "We remain committed to getting any and all Americans that want to leave, to get them out. We still believe – certainly now that we have been able to increase the capacity and the flow – we believe that we have the ability to get that done by the end of the month." 

Kirby later said that about 4,000 Americans have been evacuated from Afghanistan so far.

CLICK HERE TO GET THE FOX NEWS APP

The Pentagon has declined to reveal exactly how many Americans are currently trying to flee Afghanistan, saying only that "several thousand" remain. Biden said he had instructed Secretary of State Tony Blinken to provide an update on the number of Americans left in the country by Wednesday.

Psaki indicated during a news briefing Tuesday afternoon that the president was open to extending the deadline, against the Taliban's wishes, if Americans remained in the country past that date.

Fox News' Lucas Tomlinson contributed to this report.