WASHINGTON -- Afghan Taliban militants now control about half of the war-torn country's 419 district centers, a top US general said on Wednesday.

"Strategic momentum appears to be sort of with the Taliban," General Mark Milley, chairman of the US Joint Chiefs of Staff, told a press conference.

"There's a possibility of a complete Taliban takeover, or the possibility of any number of other scenarios," Milley said. "I don't think the end game is yet written."

While the militants have yet to capture any of the country's 34 provincial capitals, they are pressuring about half of them, said Milley.

Afghan security forces are consolidating their positions to protect those major urban centers including Kabul, he said.

The Afghan provinces have been the scene of heavy battles between Taliban and the government security forces since the start of withdrawal of the US-led forces from Afghanistan early May.

US President Joe Biden has set a formal end to the US military mission in Afghanistan for Aug 31, days ahead of his original Sept 11 deadline.

US Central Command said last week over 95 percent of the withdrawal had been completed.

More than 2,400 US troops have been killed in Afghanistan over the past two decades, with 20,000 wounded, according to the Pentagon. Estimates show that over 66,000 Afghan troops have been killed, and over 2.7 million people have had to leave their homes.