The attack by Iranian-trained militias using Iranian-made kamikaze drones against U.S. forces in Jordan, which killed three American servicemen and injured at least 34, serves as a microcosm of a much larger problem: America’s deterrent capability and deterrent credibility have been eroded by a range of factors. These include a quarter-century of underinvesting in defense; years of believing the words of tyrants, rather than using their actions as a guide for policy; disunity within the Free World, fueled by American administrations as well as allied governments; and the withdrawal from Afghanistan, which was thoughtlessly negotiated by the Trump administration, recklessly executed by the Biden administration and deeply damaging to America’s word.

“We shall respond,” President Biden vows. Responding is the right course of action, but the hard truth is that the administration’s responses to Iranian attacks to date have been too little and too late. Given that there have been 150 such attacks in recent months, we are lucky that only three American personnel have been killed. Our enemies do not view delayed and “proportionate” and “limited” responses as signs of strength—and are clearly not deterred by such responses. 

Thus, the urgent task of restoring deterrence must be pursued on two fronts. The first is Iran’s neighborhood. As thoughtful retired flag officers have argued, the Biden administration must deliver punishing blows against things Iran’s outlaw regime holds dear. Those things, by and large, are not located in Syria and Iraq. President Reagan’s Operation Praying Mantis (which sank most of Iran’s navy on an afternoon in 1988) is a template, as is Operation El Dorado Canyon (which targeted Libya’s terrorist infrastructure in 1986). The counterpoint to those who worry this will trigger escalation is that Iran has already climbed the escalation ladder. 

The other front where deterrence must be restored enfolds domains and theaters well beyond Iran’s neighborhood. After decades of watching the Free World shortchange defense, an Axis of Autocrats—led by Beijing, Moscow, and Tehran, working with proxies and partners in North Korea, Venezuela, Cuba, Nicaragua, Serbia, Belarus, Syria and the Hezbollah-Hamas-Houthi hydra—senses weakness and is moving against that weakness. For more than a decade, America has invested barely 3 percent of GDP in defense. (The Cold War average was more than twice that.) Thus, America’s Army is trying to deter war in Europe with one-third of the soldiers it deployed during Cold War I. With only 20 stealth bombers in service, just 14 percent of the Air Force bomber fleet would be able to penetrate Russia’s or China’s air defenses. Navy leaders say they need 500 ships; they have 296. These numbers, along with the very limited and very delayed responses to Iranian militia attacks on land and Iranian-Houthi attacks in the Red Sea, suggest that conducting another Praying Mantis or El Dorado Canyon may not be possible for today’s military—or may not be possible without leaving other regions vulnerable and exposed to attack.

Wise leaders recognize that military readiness paradoxically keeps the peace. “If you wish for peace, prepare for war,” the Romans counseled. President George Washington put it more genteelly, explaining, “There is nothing so likely to produce peace as to be well prepared to meet an enemy.” President Reagan matter-of-factly noted that “None of the four wars in my lifetime came about because we were too strong…Our military strength is a prerequisite for peace.”

Restoring deterrent credibility (through punitive actions) and deterrent capability (through long-term investments and immediate policy shifts) is not without risk. But as Reinhold Niebuhr wrote during an earlier time of testing, “We take, and must continue to take, morally hazardous actions to preserve our civilization.”