In the 18 years since the unprovoked and dastardly attacks on the World Trade Center and Pentagon, the United States has been fighting the Global War on Terror, or what we have often called the Long War. And America has learned some lessons. There are also some very harsh truths that we must accept and deal with.

The first lesson is that terrorism was not and is not a “law enforcement” issue and addressing it as such is a huge mistake. To see why, read this 2009 post from 9/11 Families for a Safer America, especially the parts about discovery requirements. Andrew McCarthy, a federal prosecutor, explains what discovery did in detail in this 2006 piece in The Wall Street Journal.

Tied in with this is a harsh truth: The work of gathering intelligence, especially human intelligence, is very difficult and it involves doing a lot of distasteful stuff. It isn’t just enhanced interrogation. You have to induce someone with information you need for America’s national security to betray their country. At best, you’re dealing with someone who is appalled by what his or her country is doing. More likely, you’re paying them off with money. Or you are getting their cooperation through some form of extortion or blackmail involving skeletons in their closet. As such, it is something presidents will shy away from, and Donald Trump is no exception (if you believe CNN’s fake news).

The next lesson learned: We need to have the backs of those who step up to protect this country. Whether it’s making sure the wounded are cared for, that returning vets can transition to civilian life, or even making sure that their service is not denigrated, America must step up for the Patriots in both the military and the intelligence community. We learned the lesson for the former in the wake of the Vietnam War.

The harsh truth is that we haven’t done so, especially in the case of the intelligence community. In fact, the CIA has had it the worst: In the wake of 9/11, Americans were willing to do what it took to keep the country safe, but as memories faded, we allowed a number of politicians to turn on the intelligence community for political gain. In the process, Patriots like James Mitchell, Jose Rodriguez, and Gina Haspel, who took part in the enhanced interrogation program, have been publicly smeared in the best of circumstances, and are being persecuted by the “Gitmo Bar” at worst. Seeing this, is it any wonder that our enemies think they can wait us out?

Which leads to another lesson: We should always assume we have underestimated the difficulty of victory. In the wake of 9/11, George W. Bush was correct to go for victory, but his biggest mistake was not asking for a massive military buildup in terms of force structure. In World War II, America made a massive military buildup. At the end of the war, many planned ships, planes, and tanks were canceled, but that was when victory was practically assured. The reason Desert Storm was relatively easy and with such a low casualty count was precisely because we had a military ready for the worst (World War III with the Soviet Union).

The harsh truth of today is that by not building up the military after 9/11, we have badly limited options. In Afghanistan and Syria, America has defaulted to a “let Special Operations Command handle this” mentality. That has led to a major price being paid by these heroes, and may have contributed to some recent controversies, especially while the rest of the military gets back in shape to deal with a resurgent China and Russia.

This leads us to a very profound lesson: We need to remember 9/11 and put that into the same pantheon as Pearl Harbor, the battleship USS Maine, and other reminders of what the lack of preparedness can cost us. “We the People” are ultimately responsible for ensuring those elected to office keep our military ready to defend this country.

The harsh truth is, though, that in the case of too many Americans, the answer to the question posed by Darryl Worley’s 2004 hit song, “Have You Forgotten?,” is “Yes” in some very key regards. We should be able to see the unvarnished news coverage of what happened that day — and not allow politicians, the media, and Silicon Valley to “manage” our remembrance of that horrific day.

The lessons of the Global War on Terror have come at a huge price. Some of it was paid on 9/11, a fair bit paid afterwards. But we need to learn those lessons and accept the harsh truths in order to keep this country safe. The alternative is seeing another 9/11 — or something worse — take place.