US President Joe Biden announced on Friday the arrival of the first batch of Afghans who worked for the US military on a flight to the United States, at the start of an operation to evacuate thousands for fear of possible retaliation by the Taliban.

About 20,000 Afghans worked for the United States after the invasion in the aftermath of the September 11, 2001 attacks.

They applied for evacuation under the Special Immigrant Visa Program, which is overseen by the Department of State.

Some estimate that the total number of people who will be evacuated under Operation Allied Sanctuary will reach 100,000 after accounting for family members.

Many of them fear reprisals from the Taliban movement, which is now controlling large areas of the country, since the foreign forces began the first phase of their withdrawal, which is expected to be completed in late August.

"Today marks an important milestone as we continue to deliver on our promise to the thousands of Afghan citizens who have served alongside American forces and diplomats for the past 20 years in Afghanistan," Biden said in a statement released by the White House.

National Security Council official Russ Travers said that the first group, which includes about 200 people, will complete health and other procedures before sending its members to new homes across the country.

"All of them have completed rigorous security checks conducted by intelligence officials and the national and internal security agencies," he added.