Nineteen years ago, the United States invaded Iraq, optimistically wading into its greatest foreign policy blunder since the Vietnam War.

Faulty intelligence, deliberately curated by an administration politically dead set on invasion, convinced the American people, recently shaken by September 11, that entering Iraq was the only option available to prevent a mad tyrant from unleashing terrorism and weapons of mass destruction on the world. Americans were told that the war would not last long, and that it would establish a stable democracy, contributing to a more secure Middle East.

I was a fifth grader in 2003, and the debates leading into the war were the first foreign policy issues I fully comprehended in real-time. As the son of an airline pilot, I was indelibly affected by September 11. I remember my fear and sadness from feeling that war was necessary to stop Saddam Hussein from using WMDs or from empowering people who could endanger my father. I felt pride as my dad, also a Navy veteran, took part in the Pentagon’s Civil Reserve Air Fleet program to fly troops to the Middle East for Iraq deployments. I was transfixed for days by the non-stop coverage of the invasion.

Many Americans can think back to those days as we tried to make sense of a post-9/11 world and what America’s role in that world should be.

We now know that Hussein never had substantial links to al-Qaeda nor possessed WMDs. Protracted nation-building followed America’s quick conventional victory, revealing the limits of our ability to spread liberal democratic values by force rather than by example.

The cost of the invasion has been devastating — 4,500 American service members killed, 32,000 wounded, tens of thousands of veterans lost to suicide, hundreds of thousands of Iraqis killed and wounded, and $2 trillion spent by American taxpayers.

And rather than stabilizing the Middle East, the war unleashed sectarian violence in Iraq and ushered in an era of strategic turmoil still felt today.

The biggest beneficiary of toppling Iraq’s government was Iran, whose influence across the region has swelled since. The chaos also created conditions for the emergence of ISIS, a threat American troops are still deployed to counter a generation later.

These terrible outcomes occurred because policymakers lacked a prudent, disciplined policy framework that recognized America’s fundamental security, the limits of its power, and the risks of overextension.

It’s cruelly ironic that the man best positioned to have opposed this war did the most to convince ordinary Americans it was necessary.

Colin Powell learned the bitter price of strategic hubris while serving in Vietnam. Later, as the chairman of the Joint Chiefs of Staff during the Persian Gulf War, General Powell helped avoid a bloody quagmire for U.S. forces by keeping the war limited.

Based on those experiences, the “Powell Doctrine” offered a vision of an American foreign policy that might have been.

The Powell Doctrine argues that the United States should only resort to military force when its vital national interests are threatened, clear and achievable objectives are present, overwhelming force necessary for the objectives is available, diplomatic options have been exhausted, and an exit strategy is in place.

In retrospect, it’s clear that the decision to invade Iraq in 2003 didn’t meet any of these requirements.  

Nevertheless, conflicted by a sense of duty, Powell used his hard-won credibility to buttress the Bush administration’s own faulty intelligence about WMDs. Powell’s speech to the United Nations Security Council convinced many ordinary Americans that war was necessary and proved an infamous turning point in America’s reputation abroad as the statements made turned out to be false.

Powell later regretted not having the moral courage to resign in protest of the march to a war he opposed. Had he stuck to his own foreign policy convictions, he wouldn’t have needed to feel that regret.

If the Iraq War tragedy is to teach us anything it is that a realistic and restrained foreign policy, like that of the Powell Doctrine, is the best path forward.

Those who bore witness to the grave mistake of the invasion have a responsibility to educate future generations about what serves our national interests and the unintended consequences of wars that do not serve them. Younger Americans need to understand how a society can whip itself into a pro-war fever pitch and what can be done to combat the default to military action. Most of all, we must prepare future generations to show the courage Colin Powell lacked to speak out against foreign policy errors, even when doing so is unpopular.

Reviving the Powell doctrine means bringing an end to endless wars that fly in its face, reasserting congressional war powers to more deliberately debate whether to enter conflicts, repealing outdated authorizations for the use of military force, and rededicating ourselves to a more humble, achievable foreign policy that best protects American interests.

The Iraq War should remind us that American power is most potent when it’s used judiciously, as laid out in the Powell Doctrine. Our leaders must never again put American troops into harm’s way without a clear connection to our national interest and achievable mission to carry out.

To honor those who served and sacrificed in Iraq as we reflect on the last 19 years, our nation must pursue a more thoughtful, responsible foreign policy.