Each generation has a defining moment where every American can recall exactly where they were when the world seemingly stood still. On the morning of September 11, 2001, I was a major in the United States Air Force with orders to the Pentagon. I was in an exit interview with my operations group commander, Colonel Cameron Bowser, and what happened next was both a mark of exceptional leadership and a demonstration of American resolve that has since defined the generation of post-9/11 veterans.

Shortly after 8:46 AM, my interview with Colonel Bowser was interrupted when his executive officer knocked on the door and entered the office: “Sir, an airplane has hit one of the Twin Towers in New York City. They’re not sure what kind of plane, but they think it was an accident.” Colonel Bowser thanked the executive officer for the information and we returned to the interview. Then a few minutes later, around 9:03 AM, the executive officer burst back into the office with the additional news that a second airplane had hit the towers. This was the moment we realized this was no accident and our nation was under attack.

In this unprecedented moment, Colonel Bowser did the most remarkable thing. He asked the executive officer to leave the office and close the door. After a measured pause, he turned to me and said, “Nina, this is your new enemy, and will now be the focus of the rest of your career.” For Colonel Bowser to take that moment to pause, in the middle of an unfolding crisis, to look me in the eye with calm resolve and provide insight was the label of outstanding  leadership that still resonates with me today.

And he was right.

Our new reality, and Colonel Bowser’s resolve, was also reflected in my unit in the events that followed. As we learned more of the attacks in real-time, my unit was directed to go home in case the attacks would also target our base — but no one did. Each and every Airman in my unit refused to leave the base, opting to remain at their post to defend our Nation that was now under attack.

That resolve continued in the months and years after the day that has since become known simply as, “9/11.” To this day, I am both astounded and inspired by the Airmen, Soldiers, Sailors, Marines, Coastguardsmen, and Space Force Guardians that have since responded to the call and demonstrated resolve in the face of emerging threats and a changing reality. They not only held their post that day and kept it late into the night, they volunteered to deploy to Afghanistan and Iraq to combat terrorism and defend our Nation by going directly into the battle.

So as the images of that fateful day will inevitably flood our media streams on this somber anniversary date 25 years later, I will be remembering Colonel Bowser and reflecting on three realities I know to be true.

First, our Nation is still vulnerable. Make no mistake, we are the greatest air, space, cyberspace, land, sea, and undersea force the world has ever known. But it’s that very preeminence that makes us a target and puts us at risk both as a military force and as a country. We are relentlessly subjected to cyberattacks all day, every day, and that carries direct implications for our critical infrastructure which provides energy, water, fuel, and power to our communities. We rely heavily on space capabilities for position, navigation and timing, as well as communications, weather forecasting and more. But like our critical infrastructure on the ground, these satellites and space systems are also vulnerable to AI-enabled cyber attacks. In this relentless and ever-evolving warfighting environment, our adversaries Russia and China are not only outpacing our ability to build hypersonic missiles, drones, and counter-space systems, but they’re also collaborating against us as they do.

Second, most Americans aren’t aware of these vulnerabilities or the foreign threats to our way of life. There’s still a fair amount of education, public disclosure, open dialogue, and honest exchange that needs to happen. The United States Space Force is providing a solution, publishing a summary of space-related threats on a quarterly basis. But the average American doesn’t know this resource exists or even the reason why it needs to exist in the first place. The purpose behind the Space Force’s efforts, however, is for the public to be knowledgeable of these vulnerabilities and threats so that together we can help devise solutions, engage in policy debate and vote on budgets that bolster our collective resilience. It’s going to take a whole-of-government approach to address these vulnerabilities and threats, which will also require industry, academia, Congress, and the voting public to be part of the solution.

Third on my mind will be my most precious thought: the first responders on 9/11. The same tragic images that will be on our media streams on this 25th anniversary will also include these American heroes, who ran into the throat of chaos toward the smoke, fire, falling buildings, and downed aircraft. These first responders demonstrated the same bravery and resolve as the Airmen on my base that day, who donned kevlar and manned their guns to protect our post late into the night.

We often place heroes on a pedestal, as we should. But when we ask, “Where do these heroes come from?” We only need to look to our left and to our right: the American heroes who choose to serve our Nation as first responders and military service members are among each and every one of us. They remain committed to keeping us safe and secure day in and day out. There is also no shortage of them — generation after generation, the men and women of our great Nation always have and always will face down any terror or threat that comes our way. This is a defining feature of American resolve that was on display 25 years ago and continues into the present day.

So on the twenty-fifth anniversary of that fateful day, the American public can rest assured that our American heroes, as they did on 9/11 and the years that followed, will always answer the call when our Nation needs them in a steadfast demonstration of exceptional leadership and American resolve.