In an address delivered from the Oval Office on the evening of March 19, 2003 — 20 years ago today — President George W. Bush announced that the United States and its allies had embarked on a military campaign “to disarm Iraq, to free its people, and to defend the world from grave danger.” Like the overwhelming majority of Americans at the time, I supported the decision to go to war and put an end to the regime of Saddam Hussein.

Two decades later, I remain certain that the decision to overthrow Saddam was correct. That is no longer the popular opinion and hasn’t been for a long time. In many quarters, the conventional wisdom long ago took hold that the invasion of Iraq was premised on the falsehood that Saddam was stockpiling weapons of mass destruction, a falsehood that Bush recklessly exploited in his zeal to topple Saddam. “Bush lied; people died” became the brutal shorthand for that view. But that calumny doesn’t stand up to scrutiny.

As in every war America has ever fought, terrible mistakes were made in Iraq. After removing Saddam from power, the US-led coalition was too slow to put Iraqis in charge of their government, too quick to disband the Iraqi army, and too short-sighted to anticipate the savage insurgency led by Saddam’s loyalists and Islamist fighters. Because of those failures the war lasted much longer than it should have and cost far, far too many American and Iraqi lives.

But if the Bush administration deserves criticism for the way it governed Iraq after the invasion, the invasion itself was clearly justified. Saddam was a malignant and dangerous dictator who not only ruled Iraq with horrific cruelty but also posed an ongoing threat far beyond his borders. He was a psychopath who had amassed a record of war crimes with few parallels in modern history. During his quarter-century as president of Iraq, he launched unprovoked wars of aggression against neighboring countries, murdered at least 50,000 Kurdish civilians in genocidal attacks, and engaged in torture on a systematic and terrifying scale. He was, in The Washington Post’s words, “one of the contemporary world’s foremost sponsors of terrorism.” He was responsible for two of the largest military conflicts in the last decades of the 20th century — the eight-year Iran–Iraq war, in which 1 million people were killed, and the Gulf War triggered by his invasion of Kuwait in 1990. And not only had he long pursued and developed weapons of mass destruction, but he had used them — deploying chemical weapons on the battlefield against Iran and to carry out the mass murder of the Kurds.

In the wake of the Gulf War, the United States and its allies made strenuous attempts to contain Saddam. Via 16 UN Security Council resolutions, Iraq was subjected to economic sanctions, ordered to dismantle its stockpiles of WMD, and required to submit to UN weapons inspectors who could verify its compliance. US and British aircraft began patrolling “no-fly zones” over northern and southern Iraq.

But Saddam thwarted every effort to keep him boxed in. He brazenly obstructed the weapons inspections and found ways to bypass economic sanctions. In 1995, when Saddam’s son-in-law defected to the West, inspectors learned that Iraq’s WMD programs were far more extensive than they had realized. By 1998 there was a strong consensus in Washington that Saddam was such a menace that he had to be ejected from power. In October 1998, more than two years before Bush was elected president, President Bill Clinton signed the Iraq Liberation Act. Passed by sweeping bipartisan majorities in the House and Senate, the law made it an explicit goal of US policy “to support efforts to remove the regime headed by Saddam Hussein from power in Iraq.”

Saddam doubled down. He expelled the UN’s weapons inspectors and refused to cooperate with the International Atomic Energy Agency. President Clinton ordered 70 hours of bombings and cruise missile strikes on Iraqi military and WMD sites. To no effect: Instead Saddam began firing at the US and British planes patrolling the no-fly zones.

Among Democrats and Republicans alike, there was a recognition that as long as Saddam remained in power, he would pose an ominous threat. Then-senator Joe Biden said at a Senate hearing in 1998 that “taking this son of a — taking Saddam down” was the only way the United States would be able to disarm Iraq of its weapons of mass destruction.

But with the 9/11 attacks, US concerns about Saddam grew infinitely more pressing. Terrorism was not a new phenomenon, but terrorism designed to cause mass destruction and bloodshed was. Suddenly it became a matter of intense urgency to keep WMD out of the hands of terrorists. Saddam had not been involved in 9/11. But given his history of using WMD, his many connections with terrorist organizations, and his utter disregard for the rule of law, the Bush administration came to believe that it would be unthinkable to let him remain in power. Congress agreed, voting by lopsided majorities to authorize US military force against Iraq.

In November 2002, the UN Security Council unanimously adopted a 17th resolution offering Iraq “a final opportunity” not just to disarm but to demonstrate that its stockpiles of biological and chemical weapons had been destroyed. As the world later learned, those stockpiles were (mostly) gone. But the world didn’t know it at the time — the assessment of virtually every international intelligence agency and observer was that Saddam was hoarding WMD. Even Iraqi military officers were sure there were caches of the illicit weapons. All the while, Saddam refused to provide the Security Council with the required evidence proving that he had disarmed.

But if the intelligence agencies were wrong about the existence of WMDs, they were right about Iraq’s undiminished ability to produce them. Several months after Saddam was overthrown, David Kay, the chief US weapons investigator in Iraq, confirmed to Congress that the intelligence about WMD stockpiles had been wrong. He also testified that Saddam’s covert weapons capacity remained intact. “We have discovered dozens of WMD-related program activities and significant amounts of equipment that Iraq concealed from the United Nations during the inspections that began in late 2002,” Kay reported. Weapons inspectors would later conclude that Iraq had all along maintained the ability to produce deadly biological and chemical agents on short notice.

In the public mind, the invasion of Iraq was predicated on the existence of WMD stockpiles. When they didn’t materialize, the Bush administration’s credibility suffered a serious blow. Politics being what it is, the president’s foes were quick to attack Bush for having “lied” the country into war. But a broad intelligence failure is not a lie. More important, the supposed weapons stockpiles were never the chief reason for going to war. Bush’s primary case for regime change was the undiminished threat posed by Saddam to Iraq’s neighboring countries and, through collaboration with terrorists, to the US homeland.

Bush “went to war,” writes the noted historian Melvyn Leffler in a new history of the Iraq war, not for oil or for democracy “but to remove a murderous dictator who intended to restart his weapons programs, supported suicide missions, and cultivated links with terrorist groups.” Were the war’s steep costs ultimately justified by its accomplishments? That is a subject of ongoing debate and, like most wars, will likely fuel disagreement for years to come. But the war was undertaken in the first place to remove one of the world’s bloodiest and most aggressive tyrants from power, and to prevent another horror like 9/11 from occurring on US soil. Even from the perspective of 20 years, those were legitimate goals. More than legitimate, they were honorable.