Nuclear deterrence makes the most sense at the most basic level: nuclear weapons deter use by an adversary for fear of retaliation in kind. Deterrence, therefore, requires survivable nuclear capabilities. From this fundamental requirement, there are now approximately 15,000 nuclear weapons in the world. Most of them are in the United States and Russia. The explanation for why there are so many lies in the layers of nuclear orthodoxy and doctrinal complexity that have accumulated like sediment atop the foundation of nuclear deterrence.

One gets to thousands of nuclear weapons by subscribing to requirements for extreme redundancy—not just a nuclear triad of bombers, submarines, and land-based missiles, but also air- and sea-launched cruise missiles to accompany them. Some missiles and all bombers carry more than one warhead. Massive targeting lists are needed to make sense of large numbers of warheads. Add to this the requirement to launch within minutes of learning about a nuclear attack. Add also short-range, “tactical” nuclear weapons. Then add the option of using nuclear weapons first as well as in retaliation.

It is this superstructure of beliefs about nuclear deterrence that leads to high warhead numbers. Few explain such beliefs in detail because they sound so Strangelovian, and most take them on faith since the United States managed to survive the Cold War without nuclear warfare. We choose not to think about the close calls, and we assume that our national leaders will recognize the craziness of the nuclear war-fighting plans. But add in the prospect of a person with deeply suspect personality traits becoming president and the expansive belief system atop nuclear deterrence seems quite worrisome.

An anti-nuclear demonstrator protests in Parliament Square in London March 14, 2007. Stephen Hird / Reuters During and after the Cold War, the United States looked to treaties to alleviate its concerns about nuclear weapons. Now treaties are unraveling, and nuclear orthodoxy has made a comeback, thanks to Russian President Vladimir Putin’s actions and U.S. and Russian strategic modernization programs. The tab for recapitalizing the U.S. triad, plus cruise missiles, plus life cycle costs, runs to approximately one trillion dollars. Because Washington never got around to questioning nuclear orthodoxy, it now finds all of these programs necessary and finds it hard to accept downsizing.

Let’s give nuclear deterrence its due: offsetting nuclear capabilities have helped prevent full-scale conventional wars between major powers since 1945. They have also induced caution during crises and during the two limited conventional wars that have been fought between nuclear-armed states. As long as nuclear weapons exist, nuclear deterrence will be needed. But nuclear deterrence doesn’t require so many weapons or such complicated nuclear war-fighting plans.

U.S. President Barack Obama fields a question during his press conference at the conclusion of Nuclear Security Summit in Washington April 1, 2016. Kevin Lamarque / Reuters To believe in nuclear orthodoxy requires either the wholesale suspension of disbelief that nuclear war-fighting plans can be usefully employed or an otherworldly belief in the ability of national leaders to control damage once the nuclear threshold has been crossed. Defenders of nuclear orthodoxy assert that they are supreme realists, but it is not realistic to presume meaningful brain function in the limited time structured for some limited uses of nuclear weapons or for their wholesale use.

Further, after the first mushroom cloud appears, everything depends on escalation control, not “credible” deterrence and war-fighting options. Indeed, once the nuclear threshold is crossed, the belief system surrounding nuclear orthodoxy becomes flimsy and brittle; the “pacifying logic” of deterrence theory implodes with first use.

Nuclear deterrence theory works until it fails, and then the foremost danger is that it will fail catastrophically. The prevention of catastrophic failure rests on extremely limited use, after which national leaders might somehow be able to intervene to stop the madness—even though they have failed to prevent a war.

Absent orthodoxy-busting leaders such as Ronald Reagan and Mikhail Gorbachev, the path of least resistance (although it still prompts great resistance) is to down-build nuclear arsenals one decrement at a time. This process is slow going and prone to disruption. More progress will become possible if leaders take a hard look at the belief system that has produced this huge, deathly monument to wishful thinking.

There has never been an ideal time to fundamentally reassess the most extreme tenets of nuclear orthodoxy—not during the Cold War, not during big drawdowns after the Soviet Union dissolved, and not now, with Vladimir Putin’s landgrabs and saber-rattling. But the presidential candidacy of Donald Trump demands reassessment of this belief system, which is very expensive to maintain and which cannot withstand serious scrutiny.