Mention the phrase “civil defense” to most younger Americans, and you will likely enter the realm of unintended hilarity. The image that comes to mind is usually the notorious “Duck and Cover” film, in which Bert the Turtle instructed children how to avoid death during a nuclear attack by hiding under their desks. Such official misinformation (or so it seemed) was comprehensively pilloried during the much-praised 1982 documentary Atomic Café. Civil defense during the era of the hydrogen bomb? What a lunatic delusion.

The problem is that throughout modern U.S. history, even during the “Duck and Cover” years, civil defense in various forms has been valuable and necessary—and its significance is today greater than it has been for decades. We must understand how the hostile critique originated and the myths on which it is based.

Civil defense is a complex and multi-layered concept. There is not a simple up-down choice in which a country either practices civil defense or decides to forgo it. Civil defense includes, for instance, preventing enemy attacks on the territory of the homeland and the civilian population, and reducing the harm of successful assaults. More broadly, civil-defense policies might involve organizing defense against spies and saboteurs, a necessary but risky strategy that historically has sometimes shaded into vigilante actions against dissenters.

Through much of the past century, leftist and liberal groups have often been hostile to civil-defense policies, partly owing to civil-liberties fears. More generally, the objection is that stressing the need to defend against foreign powers stirs paranoia against those nations and actively contributes to warmongering. To prepare for war, in this vision, is to promote it. Such objections became all the more acute after 1945.

Atomic Café was released at the height of liberal hostility to Ronald Reagan’s hardline policies against the Soviet Union, and it has to be seen as a weapon in the ongoing polemic. From a left-liberal perspective, the only authentic way to defend U.S. civilians in the modern world is to achieve peace abroad through negotiation and compromise.

The problem with this perspective is that on occasion the U.S. genuinely does find itself facing foreign foes, who really do target the homeland. In the early months of the Second World War, the U.S. suffered terribly from inadequate civil-defense programs. That became evident in the early lack of blackout regulations in major East Coast cities. In consequence, German U-boats relied on those urban lights to silhouette large ships and oil tankers sailing along the coast, and took a crippling toll. (For that reason, German skippers loved to sail off Atlantic City and Miami.)

Civil defense became an active necessity with the growing Cold War confrontation from 1946 onward, when it was certain that any global war would involve direct attacks on U.S. territory. Looking at these years, it is essential to avoid the blinders of the post-1960s world, in which any superpower confrontation would be fought out by intercontinental ballistic missiles (ICBMs) and colossally destructive hydrogen bombs, which really would endanger the continuance of the human race. From 1970, the arrival of MIRV weapons (multiple independently targetable reentry vehicles) made it virtually impossible to stop such an attack once it was launched. We were definitively in the age of Mutual Assured Destruction.

But matters were very different in the pre-MAD years. Before (say) 1958, the most likely scenario was that the Soviets would indeed attack the U.S. homeland, initially by means of manned bombers and later missiles, but would be limited in their use of nuclear weapons. The Soviets tested their first fission bomb in 1949, with a hydrogen weapon following in 1953, but they still remained several years far behind the U.S. in delivery systems. They could hit some areas but not others, and it would be a good while before they could comprehensively destroy U.S. targets. We get a sense of this strategic situation from the U.S. concentration of its military resources in the heartland, away from the imperiled coasts. The main American strategic air forces were sensibly concentrated far inland, at centers like Offutt (Omaha, Neb.) and Dyess (Abilene, Texas). That geographical imperative was what made the Soviet deployment of missiles in Cuba in 1962 an existential threat. Overnight, the entire U.S. homeland was menaced.

American civilians in the 1950s thus faced some risk of nuclear attack, but it very much depended on their location. If we imagine, for instance, a Soviet attack in 1952, during the Korean War, that would conceivably involve 20 or so Nagasaki-sized bombs annihilating centers like New York, Pittsburgh, and Los Angeles but leaving large parts of the country free from direct blast effect. In such a situation, civil defense made wonderful sense. An atomic bomb dropped on Manhattan (say) would be a catastrophe for the five boroughs, but there were plenty of wise precautions that civilians could take further afield, in Allentown or Buffalo. They could stockpile food and water, build bomb shelters and survival rooms, and prepare to respond to fallout. Properly done, civil defense at this stage might have saved millions of lives.

Over time, though, technological changes made such policies obsolete. The “Duck and Cover” film offered excellent advice when it was first screened publicly in 1952; by 1982, it had been overtaken by technology and was irrelevant or worse.

In those early pre-MIRV days, the U.S. also plausibly could have hoped to stop some or all of the bombers and missiles from getting through. U.S. commanders were after all well aware of how effectively German anti-aircraft defenses had almost crippled their own bomber offensives in 1943–44. It’s largely forgotten today, but American cities were surrounded by batteries of radar-guided anti-aircraft guns, and later by Nike missiles. By 1962, 240 Nike Ajax launch sites were operational within the U.S., and the Ajax was subsequently replaced by the nuclear-armed Hercules. Even today, newspapers around the country regularly publish “believe it or not” stories about the surviving remains of these disused Nike sites, with their bunkers and guardhouses, and looking like fortresses from Game of Thrones.

The effort to defend the cities culminated in the late 1960s with schemes for comprehensive anti-ballistic missile (ABM) systems. But what was next? Would there be a new arms race, as the Soviets developed their own anti-ABM weapons, and the Americans responded with anti-anti-ABMs, and so on? And if the ABM system was to be as effective as was claimed, might the Soviets decide on a preemptive nuclear strike before it was implemented? Resulting concerns led to the U.S.-Soviet ABM Treaty of 1972, which in practice left most cities open to missile attack.

Technological advances thus overwhelmed the civil-defense idea, at least in any traditional sense. No, digging backyard shelters would not be of much use today against a mass onslaught of Russian (or Chinese) ICBMs.

But today, those are by no means the only nuclear scenarios that the country faces, or even the most plausible. Apart from terrorist assault, by far the most likely nightmare presently would be an attack by North Korea, perhaps with one bomb or at most a handful. In a sense, we would be back to the strictly limited nuclear threat that prevailed in 1952, and once again, civil defense would be an essential consideration. Even if we suffered the cataclysm of losing San Francisco, the people of Los Angeles or Seattle could still take many steps to protect their life and health. A public-education program would be an excellent idea, and the sooner the better. And critics can make all the jokes they like about “Duck and Cover.”

Civil defense will always be seen as paranoid, until it becomes a matter of life and death.

Philip Jenkins teaches at Baylor University. He is the author of Crucible of Faith: The Ancient Revolution That Made Our Modern Religious World (forthcoming Fall 2017).