"We cannot afford to be in that situation again," Allvin wrote. "The insights I gained then have been validated in the years since, and serve as motivation for what we in the Air Force community need to strive to achieve when it comes to family readiness."

Sweeping changes to the force came earlier this year. In February, Allvin and other Department of the Air Force leaders rolled out numerous changes ranging from bringing back warrant officers, reorganizing training organizations and creating new offices. The changes all underscore the need to prepare for a looming conflict: potential control and invasion of Taiwan by the Chinese Communist Party. 

The memo is one of the first indications of some family- and mental health-related changes the force is making in that reorganization effort.

Katherine Kuzminski, a senior fellow at the Center for a New American Security think tank who studies military personnel and family policy, told Military.com on Tuesday that the memo's comparison to how service members and their families were caught off guard by terrorist attacks in 2001 is notable.

"I think it's an apt comparison, just in the fact that in the lead-up to 9/11 the military was much more domestic, and they weren't deploying in the large numbers that we saw, and it really did matter that perhaps the support structures weren't in place," Kuzminski said. "The family readiness groups handle everything from training and advising families on how to just go through all the paperwork that comes along with the deployment, to coming up with a family care plan and family action plan."

One change has been rebranding the Key Spouse Program to the Commander's Key Support Program. That program helps connect families, spouses and single airmen to resources.

[RELATED: Commander's Key Support Program]

Volunteering opportunities have been expanded to more than just wives and husbands and now include participation for airmen, Guardians, federal employees and family members, regardless of marital status, the service announced earlier this year.

Kuzminski said that's necessary because many military spouses are working now and don't have the time or resources to devote fully to those programs.

"I think it's significant that they are changing the name from the Key Spouse Program," Kuzminski said. "Because that is another area where, in the last 23 years since 9/11, it's become evident that society has really changed, and the family readiness groups across all services have long depended on the fact that the service member who was married, that their spouse did not work."

Allvin says the service has also reshaped the Relocation Assistance Program, which provides resources and information to families making a permanent change of station move.

In a related change, airmen and Guardians with dependents who go to a professional military education or training location can now collect per diem at a Basic Allowance for Housing rate while also still receiving a housing allowance at their prior duty station for their families.

[TAKE ACTION: Ask Congress to Restore the Basic Allowance for Housing]

The Air Force is also reorganizing how it provides some mental health resources to units. Allvin explained that the service is in the process of merging the existing True North mental health programs and Operational Support Team programs to create a new resource called "True North +" that will allow officials to deploy chaplains and counselors to affected units quickly.

The service has also updated its Resilience website to connect service members and families with resources, "including crisis management tools (e.g. suicide hotline number, Military OneSource, Sexual Assault Prevention and Response, civilian Employee Assistance Program, etc.), and guidance," he wrote.

Allvin ended the memo calling for everyone, not just family members, to be prepared for potential crises and to know where they can best find resources.

"Our service needs everyone in the Air Force community, including service members, civilian employees, family members, and community partners, to work together to improve our resilience and prepare to respond in moments of crisis," he wrote. "To achieve this, I encourage everyone to contribute to family readiness by getting involved, innovating, and preparing themselves for critical moments."