American soldiers wait to board helicopters at Kandahar airbase ahead of an operation in Afghanistan on 19 May, 2003. File Photo: AFP

The US Central Command announced Monday that the withdrawal of US troops from Afghanistan has completed, ending 20 years of U.S.-led invasion into the country.

"I'm here to announce the completion of our withdrawal from Afghanistan and the end of the mission to evacuate American citizens, third country nationals and vulnerable Afghans," Kenneth McKenzie, commander of U.S. Central Command, announced during a news conference held by the Department of Defense.

"The last C-17 lifted off from Hamid Karzai International Airport on August 30, this afternoon, at 3:29 p.m. East coast time, and the last manned aircraft is now clearing the space above Afghanistan," McKenzie said.

McKenzie said while the completion of withdrawal drew an end to U.S. military presence in the war-torn nation that Washington accused of harboring Al-Qaeda -- the mastermind behind the 9/11 terror attack on American soil in 2001 -- "the diplomatic mission to ensure additional U.S. citizens and eligible Afghans, who want to leave, continues."

A CH-47 Chinook is loaded onto a U.S. Air Force C-17 Globemaster III at Hamid Karzai International Airport in Kabul, Afghanistan, on Aug. 28, 2021. (U.S. Central Command Public Affairs/Handout via Xinhua)

While paying tribute to the 2,461 U.S. service members killed -- including the 13 troops lost Thursday to a terror attack aimed at sabotaging the evacuation mission -- and over 20,000 U.S. personnel injured during the longest war Washington has engaged in throughout history, McKenzie also told reporters that no American citizens managed to embark on the final five evacuation flights leaving Kabul, meaning there were still Americans wishing to depart the country that were left on ground.

"We maintained the ability to bring them in up until immediately before departure," McKenzie said. "We would have been prepared to bring them on until the very last minute, but none of them made it to the airport and were able to be accommodated," he added.

The general said the number of U.S. citizens currently still stranded in Afghanistan is "in the very low hundreds," stressing that the Department of State is now in charge of assisting those evacuees.

A CH-47 Chinook is loaded onto a U.S. Air Force C-17 Globemaster III at Hamid Karzai International Airport in Kabul, Afghanistan, on Aug. 28, 2021. (U.S. Central Command Public Affairs/Handout via Xinhua)

"The military's phase of this operation has ended ... The diplomatic sequel to that will now begin," he said, adding that the United States will continue trying to extract the remaining U.S. citizens and "negotiate very hard and aggressively" to get eligible Afghans to come to the United States.

U.S. media cited a State Department official as saying earlier on Monday that it was believed that there were fewer than 250 American citizens who may wish to leave Afghanistan.