The adaptations required of the U.S. military for its irregular warfare since 9/11 have created a risk that American forces will lose in an armed conflict against a major power, some experts warn.

Pre-trial hearings kicked off Tuesday at the military prison in Cuba after a year-plus delay due to the pandemic. Khalid Sheikh Mohammed is the alleged mastermind of the terror attacks 20 years ago this Saturday and faces 2,976 counts of murder.

In the hours after the attacks, leaders at AFMC launched a process to immediately identify any life-saving technologies Wright-Patterson and Air Force scientists and researchers might have to assist in recovery and rescue efforts in New York City and the Pentagon.

For the children who weren’t yet born when their fathers died in the Sept. 11 terrorist attacks — more than 100, according to Tuesday’s Children, an organization that counsels them — their fathers exist only as a lifelong, heartbreaking absence.

A legacy that remains in place today and will continue to be a fact of military life for years to come in Europe: heavily fortified bases that resemble nothing like the relatively easy-access installations of the pre-attack era.

This new phase in Afghanistan could resemble operations in Somalia and Yemen, where U.S. forces have used commandos and drones to hunt offshoots of the al-Qaida terrorist network. These missions are often shrouded in secrecy from start to finish, existing in a gray area between war and peace.