US Secretary of Defense Lloyd Austin has approved a plan to transfer authority from Army General Scott Miller to Marine Corps General Frank McKenzie, Pentagon Press Secretary John Kirby said late Friday.

Miller is the commander of U.S. Forces-Afghanistan and the Resolute Support Mission. McKenzie is the commander of U.S. Central Command.

According to Kirby, this is all part of the safe and orderly retrograde that will have all U.S. troops out of Afghanistan by the end of August — well within President Joe Biden's order.

"We expect that transfer to be effective later this month," Kirby said.

"General Miller will remain in theater (Afghanistan) in coming weeks to prepare for and to complete the turnover of these duties and responsibilities to General McKenzie."

Kirby emphasized that McKenzie will retain all existing authorities that Miller currently possesses and commander of U.S. Forces, Afghanistan. "He will continue to exercise authority over the conduct of any and all counterterrorism operations needed to protect the homeland from threats emanating out of Afghanistan, and he will lead U.S. efforts to develop options for the logistical, financial and technical support to Afghan forces once our drawdown is complete."

This process will allow the United States to maintain a diplomatic presence within Afghanistan, as U.S. and Afghan leaders decide on the new bilateral relationship between the nations.

Austin also approved establishing U.S. Forces Afghanistan to be led by Navy Rear Admiral Peter Vasely in Kabul. Army Brigadier General Curtis Buzzard will lead the Defense Security Cooperation Management Office, Afghanistan that will support Vasely.

Buzzard's office is based in Qatar. That office will provide funding for the Afghan National Defense and Security forces to include over the horizon aircraft maintenance support.

Kirby confirmed U.S. forces have left Bagram Airfield and said this was a key milestone in the drawdown process.