Explanation

The most accurate reason for the U.S. leaving Afghanistan in 2021 is: As part of a planned military strategy.

Withdrawal of United States troops from Afghanistan (2020–2021).

The U.S. Armed Forces completed their withdrawal from Afghanistan on 30 August 2021, marking the end of the 2001–2021 war.

United States Armed Forces:

• Personnel: The U.S. Army had 481,254 active duty troops in 2020.
• Branches: Army, Marine Corps, Navy, Air Force, Space Force, Coast Guard.
• Founded: June 14, 1775
• Headquarters: Arlington County, Virginia, United States
• Secretary of Defense: Mark Esper