U.S. troops are still in Iraq — not to mention Syria, Afghanistan, and various African countries — to ward off or put down insurgencies. Within the national security apparatus, however, the Iraq War is old news.

As has been explained to me by senior officers who are still on active duty, the conventional wisdom today is that our military has moved on — and in an odd redux, they note that we have returned to the philosophy of 1973. Similar to how the Pentagon abandoned its doctrine of fighting counterinsurgencies and irregular conflicts in the aftermath of the Vietnam War, today’s military has shifted away from the wars in Iraq and Afghanistan. Instead of preparing to fight insurgents and guerrillas, our security establishment has refocused almost exclusively on the realm of great power conflict — in their parlance, peer or near-peer competitors such as Russia or China.

This trend away from “small wars” has been so intense that it contributed to Army’s resistance to publishing its own Iraq War Study, a project that I helped lead to its conclusion in 2016. During one of the periods that the Army was withholding publication of the completed manuscripts, a colonel in the Vice Chief of Staff of the Army’s office told me that the opposition was occurring because a study on the Iraq War did not fit the official narrative of the Army “returning to decisive action,” the jargon for “fighting other great powers like Russia with tanks, artillery, and airstrikes.” In January, the study’s two volumes were at last published online. But as a result of this ideological realignment, funds that had been allocated to spread the war’s lessons — to publish hard copies of the Iraq War Study, distribute them across the Army, and hold professional development sessions to foster discussion in the officer corps — were reallocated and never replaced.

Such resistance is deeply unsettling. The Operation Iraqi Freedom Study Group was originally commissioned because some of the Army’s senior leaders believed that a failure to learn the lessons of the Vietnam War had led us to repeat the errors of that conflict in Iraq. Army efforts to investigate what went wrong in Vietnam were haphazard and the limited studies that it commissioned were incomplete and uncritical. Lives were lost and funds were wasted re-learning the lessons of guerrilla and irregular warfare as a result of that omission, providing a difficult lesson on the importance of introspection. We cannot afford to make the same mistake again.

While we do not know whether our next war will be of the same category that we fought in Iraq, it would be folly to expunge all of its lessons. As the world continues to migrate to cities and pressures from failed or failing states push populations toward armed insurrection, it is quite possible that our next conflict could be another irregular war fought against guerrillas and insurgents. Even if we do end up facing a peer or near-peer competitor as the defense establishment is predicting, many of the lessons of the Iraq War still ring true. If we find ourselves facing such a foe, it would be highly likely that our opponents would fight us with a blend of conventional warfare—using ships, tanks, and warplanes—as well as with irregular tactics such as we faced in Iraq and Afghanistan. Blending both types of warfare, which has been called “hybrid warfare” or “conflict in the grey zone” enables our enemies to counter some of our conventional advantages asymmetrically, and challenge us symmetrically with forces that are on par with our capabilities. The use of paramilitaries or militias rather than uniformed soldiers, ambushing logistics convoys with improvised explosive devices, and hiding soldiers and resources amongst the civilian population- all staples of the Iraq conflict- are tactics that have also been used by Russia and other states because they make attribution and retaliation more difficult. It would be a dangerous proposition to hope that nation-state competitors we face in the future have not studied the war in Iraq and adapted their tactics.

We should not ignore our failures in Iraq out of embarrassment or shame. Rather than repeat the error of not learning from our mistakes after the Vietnam War, we should learn from the conflict in Iraq and capture those lessons so that our armed forces are capable of responding to a variety of threats and conflicts. Restoring the original distribution and dissemination plan for the Iraq War study would go far in communicating the importance of assimilating, discussing, and debating the lessons of a conflict whose consequences we will have to endure for a long time. Learning hard lessons and internalizing them is what our leaders owe to the members of our military as well as the citizens of our country.