Secretary of Defense James Mattis testified yesterday before Congress that, while he believes there was a chemical weapons attack in Syria, the United States is seeking proof. Inspectors should arrive in Syria in the coming days to investigate. There’s really no doubt among serious people that chemical weapons were used, but the question now is how to prove who did it. I have very—very—little doubt that Bashar al-Assad authorized the attack and his forces carried it out. Once the United States can reliably explain how it knows this, punishing coalition attacks should begin.

Theories are floating around the internet, especially popular among those opposed to further US intervention in Syria, that claim the rebels could have launched the attacks themselves to frame Assad. They also assert that the Syrian dictator would not have used chemical weapons, especially when he knew that President Trump was rapidly running out of patience with the Syrian conflict and wanted to withdraw US forces. Trump has made it clear that the US mission in Syria is to defeat the Islamic State (ISIS), and after the so-called caliphate’s ultimate destruction, the United States will declare victory and come home. Then, almost immediately, someone in Syria launched the chemical weapons attacks, prompting Trump to seriously consider further military action in Syria that would, presumably, help the rebels in their fight against Assad and his Russian and Iranian patrons.

But here’s what the false-flag, anti-strike conspiracy theorists are missing: there is already evidence that Assad has repeatedly used chemical weapons against civilians. He has done so multiple times even after he supposedly turned over his entire declared stockpile of chemical weapons as a result of the Obama-Putin deal in 2013. Secretary John Kerry infamously declared that “100 percent of the declared chemicals are out of war-torn Syria.”

Assad employed them in April 2017, which was what elicited the targeted US airstrikes. And there has been regular reporting that Assad’s forces are responsible for other repeated chemical weapons attacks, although these are smaller than the ones that happened last week.

Why does Assad use chemical weapons? To terrorize his enemies until they submit, and he’s almost always done so with impunity.

Hours after the most recent attack, rebel forces surrendered the town of Douma, a rebel stronghold, to Assad’s forces and evacuated. So, if Assad was the one responsible, and I believe he was, then his plan worked. Where he may have erred strategically is that the attack was so big that it caught the attention of world leaders.

Trump wants out of Syria; there’s no question. But in response to reports of the chemical weapons attack, he tweeted:

The reason the United States with allies should absolutely respond with crushing military strikes has to do with the kind of weapons Assad almost certainly used.

Chemical weapons serve no legitimate military utility. They do not have explosive properties necessary to blow up hardened military platforms. They are unwieldy so that they cannot be employed to accurately hit a narrow target. Chemical weapons, compared to many conventional weapons, don’t even kill that many people in a single attack (despite their being categorized as a “weapon of mass destruction”). According to aid workers, the attack on Douma reportedly claimed around 40 lives.

Chemical weapons are inherently terror weapons. After World War I, after both sides employed other new technologies and tactics that killed countless people, countries sought to ban chemical weapons even though they caused only 1 percent of deaths in the war. These weapons cause agonizing suffering, and children and the elderly, those with the weakest respiratory systems, are the most susceptible to death. But before the chemical weapons choke out their lives, they could endure convulsions, foaming at the mouth, blindness, and other horrible effects, while their family members helplessly watch.

The Geneva Protocol of 1928 sought to abolish the weapons. The Chemical Weapons Convention of 1997 improved upon the protocol. Of course, arms control is only so useful. And if they’re not enforced, they are meaningless.

Treaty or no treaty, if Assad is permitted to continue employing chemical weapons with impunity, he will successfully normalize them. US forces, our allies, and civilians in the region and around the world will be in great danger of becoming victims of the same.

The UN recently issued a report that stated North Korea has been assisting Syria in building an industrial-sized chemical weapons facility. Russia and Iran are financing Syria, providing military support and diplomatic cover for the murderous regime. The president is right to single out those countries as responsible for Assad’s actions as well, and they should pay a price, whether that’s in the form of sanctions or some other penalty.

By failing to respond to a known chemical weapons attack like the one last week, the United States is communicating to our enemies that those weapons are just like any other weapons and will be treated as such. But they are not, and so the United States with our allies, likely the United Kingdom and France, must respond.

The attack should eliminate targets related to the development and employment of chemical weapons, and it should be so crushing that it causes Assad, and those who support him, to assess that the employment of chemical weapons, whatever the strategic gain, is not—and will never be—worth the cost. That is the heart of our deterrence, assuming the use of these terror weapons is still something the United States wishes to deter, and it would be a moral and strategic failure if it was not.

Rebeccah L. Heinrichs, a contributing editor at Providence, is a fellow at Hudson Institute where she provides research and commentary on a variety of international security issues and specializes in deterrence and counter-proliferation. She is also the vice-chairman of the John Hay Initiative’s Counter-proliferation Working Group and the original manager of the House of Representatives Bi-partisan Missile Defense Caucus.

Photo Credit: A US Air Force F-22 Raptor assigned to the 380th Air Expeditionary Wing, Al Dhafra Air Base, United Arab Emirates prepares to taxi down the runway on February 13, 2018, in support of Operation Inherent Resolve against the Islamic State in Iraq and Syria. US Air Force photo by Tech. Sgt. Anthony Nelson Jr.

For further reading, be sure to see Rebeccah Heinrichs’ print edition article on nuclear deterrence and the Christian just war tradition, “A Robust Nuclear Deterrent: A Force for Peace & Justice.” Be sure to also read Alan Dowd’s explanation for how Christians should view military deterrence, “Shield & Sword: The Case for Military Deterrence.” Finally, in Providence‘s Fall 2017 issue our managing editor, Marc LiVecche, reviews the Sermon on the Mount and warfighting in “Blessed are the Peacemakers.”