The Biden administration has told U.S. commercial airlines that it could order them to provide flights for the Afghanistan evacuation, the Defense Department said Saturday.

The Defense Department informed several major U.S. airlines Friday night that it could activate the Civil Reserve Air Fleet, a person familiar with the matter said. The CRAF is a nearly 70-year-old program that was created after the Berlin airlift, to provide backup for a "major national defense emergency."

The flights wouldn't be from Afghanistan itself but from other locations, according to a person familiar with the matter. That could include flying individuals who are stranded at U.S. bases in Germany, Qatar and Bahrain, according to The Wall Street Journal, which first reported the news.

"Working with military and industry leaders, U.S. Transportation Command is supporting efforts to transport U.S. citizens, Special Immigrant Visa applicants, and other at-risk individuals from Afghanistan," the Defense Department spokesman said. He said the warning to airlines could be rescinded if the "Defense Department deems additional aircraft are not required to meet mission requirements."

The White House didn't immediately comment.

The U.S. withdrawal from Afghanistan, which was announced by Biden earlier this year, has been beset by chaos. Thousands of people swarmed the Kabul airport after the Taliban took over the city last week, sealing control of the country.

U.S. defense officials say that the military is looking for alternative ways to get Americans, Afghans and third-country nationals safely to the airport in Kabul following threats from the Islamic State, NBC News reported Saturday.

The U.S. Embassy in Afghanistan on Saturday warned American citizens not to travel to the airport "because of potential security threats outside the gates at the Kabul airport."

A White House official informed the press pool on Saturday, that, in the past 24 hours, six U.S. military C-17s and 32 charters departed Kabul. The total passenger count for those 38 flights is approximately 3,800. The White House official says that since Aug 14.the U.S. has evacuated approximately 17,000 people.

Several U.S. airlines had volunteered earlier in the week to help with the airlift of evacuees, the person told CNBC.

Bidding for the so-called CRAF flights opened Saturday and would close Monday for United Airlines flight attendants, their union, the Association of Flight Attendants, wrote in a memo.

"In order for United to be prepared in the event the United States Department of Defense advises United Airlines CRAF has been activated, bidding for CRAF operations must be undertaken immediately and over a very abbreviated time period," said the note.