“Today, the danger of some sort of a nuclear catastrophe is greater than it was during the Cold War,” warns William Perry, “and most people are blissfully unaware of this danger.”

A former U.S. defense secretary from 1994 to 1997, Perry has been an inside player in the business of nuclear weapons for over 60 years. And his book, My Journey at the Nuclear Brink, is a sober read. It’s also a powerful counterpoint to NATO’s current European strategy, which envisions nuclear weapons as a deterrent to war: The purpose of nukes “is to prevent major war, not to wage wars,” argues the Alliance’s magazine, NATO Review.

But as Perry points out, it’s only by chance that the world has avoided a nuclear war — sometimes by nothing more than dumb luck — and, rather than enhancing our security, nukes “now endanger it.”

The 1962 Cuban missile crisis is generally represented as a dangerous standoff resolved by sober diplomacy. In fact, it was a single man — Russian submarine commander Vasili Arkhipov — who countermanded orders to launch a nuclear torpedo at an American destroyer that could have set off a full-scale nuclear exchange between the Soviet Union and the United States.

There were numerous other incidents that brought the world to the brink. On a quiet morning in November 1979, a NORAD computer reported a full-scale Russian sneak attack with land and sea-based missiles, which led to scrambling U.S. bombers and alerting U.S. missile silos to prepare to launch. But it turned out there was no Soviet attack — just an errant test tape.

Lest anyone think the incident was an anomaly, a little more than six months later NORAD computers erroneously announced that Soviet submarines had launched 220 missiles at the United States. This time the cause was a defective chip that cost 49 cents — again resulting in scrambling interceptors and putting the silos on alert.

But don’t these examples prove that accidental nuclear war is unlikely? That conclusion is a dangerous illusion, argues Perry, because the price of being mistaken is so high — and because the world is a more dangerous place than it was in 1980.

A Worsening Climate

It’s been 71 years since atomic bombs destroyed Hiroshima and Nagasaki, and humanity’s memory of those events has dimmed. But even were the entire world to read John Hersey’s Hiroshima, it would have little idea of what we face today.

The bombs that obliterated those cities were tiny by today’s standards, and comparing “Fat Man” and “Little Boy” — the incongruous names of the weapons that leveled both cities — to modern weapons stretches any analogy beyond the breaking point. If the Hiroshima bomb represented approximately 27 freight cars filled with TNT, a one-megaton warhead would require a train 300 miles long.

Each Russian RS-20V Voevoda intercontinental ballistic missile packs 10 megatons.

What’s made today’s world more dangerous, however, aren’t just advances in the destructive power of nuclear weapons, but a series of actions by the last three U.S. administrations.

First was the decision by President Bill Clinton to abrogate a 1990 agreement with the Soviet Union not to push NATO further east after the reunification of Germany or to recruit former members of the defunct Warsaw Pact.

NATO has also reneged on a 1997 pledge not to install “permanent” and “significant” military forces in former Warsaw Pact countries. This month NATO decided to deploy four battalions on or near the Russian border, arguing that since the units will be rotated, they’re not “permanent” or large enough to be “significant.” It’s a linguistic slight of hand that doesn’t amuse Moscow.

Second was the 1999 U.S.-NATO intervention in the Yugoslav civil war and the forcible dismemberment of Serbia. It’s somewhat ironic that Russia has been accused of using force to “redraw borders in Europe” by annexing Crimea, which is exactly what NATO did to create Kosovo. The U.S. subsequently built Camp Bond Steel, Washington’s largest base in the Balkans.

Third was President George W. Bush’s unilateral withdrawal from the Anti-Ballistic Missile Treaty and the decision by the Obama administration to deploy anti-missile systems in Romania and Poland, as well as Japan and South Korea.

Last is the decision by the current White House to spend upwards of $1 trillion upgrading its nuclear weapons arsenal, which includes building bombs with smaller yields, a move that many critics argue blurs the line between conventional and nuclear weapons.

Strategic Uncertainty

The Yugoslav War and NATO’s move east convinced Moscow that the U.S.-led alliance was surrounding Russia with potential adversaries, and the deployment of anti-missile systems, or ABMs — supposedly aimed at Iran’s non-existent nuclear weapons — was seen as a threat to Russia’s nuclear deterrent.

One immediate effect of ABMs was to chill the possibility of further cuts in the number of nuclear weapons. When Obama proposed another round of warhead reductions, the Russians turned it down cold, citing the anti-missile systems as the reason. “How can we take seriously this idea about cuts in strategic nuclear potential while the United States is developing its capabilities to intercept Russian missiles?” asked Deputy Prime Minister Dmitry Rogozin.

When the U.S. endorsed the 2014 coup against the pro-Russian government in Ukraine, it ignited the current crisis that has led to several dangerous incidents between Russian and NATO forces — at last count, according to the European Leadership Network, more than 60. Several large war games were also held on Moscow’s borders. Former Soviet president Mikhail Gorbachev went so far as to accuse NATO of making “preparations for switching from a cold war to a hot war.”

In response, the Russians have also held war games involving up to 80,000 troops.

It is unlikely that NATO intends to attack Russia, but the power differential between the U.S. and Russia is so great — a “colossal asymmetry,” Dmitri Trenin, head of the Carnegie Moscow Center, told the Financial Times — that the Russians have abandoned their “no first use” of nuclear weapons pledge.

It’s the lack of clear lines that makes the current situation so fraught with danger. While the Russians have said they would consider using small tactical nukes if “the very existence of the state” was threatened by an attack, NATO is being deliberately opaque about its possible tripwires. According to NATO Review, nuclear “exercises should involve not only nuclear weapons states… but other non-nuclear allies,” and “to put the burden of the doubt on potential adversaries, exercises should not point at any specific nuclear thresholds.”

In short, keep the Russians guessing. The immediate problem with such a strategy is: What if Moscow guesses wrong?

That won’t be hard to do. The U.S. is developing a long-range cruise missile — as are the Russians — that can be armed with conventional or nuclear warheads. But how will an adversary know which is which? And given the old rule in nuclear warfare — use ‘em or lose ‘em — uncertainty is the last thing one wants to engender in a nuclear-armed foe.

Indeed, the idea of no “specific nuclear thresholds” is one of the most extraordinarily dangerous and destabilizing concepts to come along since the invention of nuclear weapons.

Cold Wars of Choice

There is currently no evidence that Russia contemplates an attack on the Baltic states or countries like Poland. Given the enormous power of the United States, which offers a security guarantee to NATO members, such an undertaking would court national suicide.

Nor do Russia’s recent border conflicts suggest otherwise. Moscow’s “aggression” against Georgia and Ukraine was provoked. Georgia attacked Russia, not vice versa, and the Ukraine coup torpedoed a peace deal negotiated by the European Union, the United States, and Russia. Imagine Washington’s view of a Moscow-supported coup in Mexico, followed by an influx of Russian weapons and trainers.

In a memorandum to the recent NATO meetings in Warsaw, the group Veteran Intelligence Professionals for Sanity argued as much. “There is not one scintilla of evidence of any Russian plan to annex Crimea before the coup in Kiev and coup leaders began talking about joining NATO,” the members insisted. “If senior NATO leaders continue to be unable or unwilling to distinguish between cause and effect, increasing tension is inevitable with potentially disastrous results.”

The organization of former intelligence analysts also sharply condemned the NATO war games that followed. “We shake our heads in disbelief when we see Western leaders seemingly oblivious to what it means to the Russians to witness exercises on a scale not seen since Hitler’s army launched ‘Unternehmen Barbarossa’ 75 years ago, leaving 25 million Soviet citizens dead.”

While the NATO meetings in Warsaw agreed to continue economic sanctions aimed at Russia for another six months and to station four battalions of troops in Poland and the Baltic states — along with separate U.S. forces in Bulgaria and Poland — there was an undercurrent of dissent. Greek Prime Minister Alexis Tsipras called for deescalating the tensions with Russia and for considering Russian President Vladimir Putin a partner rather than an enemy.

Greece was not alone. German Foreign Minister Frank-Walter Steinmeier called NATO maneuvers on the Russian border “warmongering” and “saber rattling.” French President Francois Hollande said Putin should be considered a “partner,” not a “threat,” and France tried to reduce the number of troops being deployed in the Baltic and Poland. Italy has been increasingly critical of the sanctions as well.

Rather than recognizing the growing discomfort of a number of NATO allies and that beefing up forces on Russia’s borders might be destabilizing, U.S. Secretary of State John Kerry recently inked defense agreements with Georgia and Ukraine.

After disappearing from the radar for several decades, nukes are back, and the decision to modernize the U.S. arsenal will almost certainly kick off a nuclear arms race with Russia and China. Russia is already replacing its current ICBM force with the more powerful and long range “Sarmat” ICBM, and China is loading its own missiles with multiple warheads.

Add to this volatile mixture military maneuvers and a deliberately opaque policy in regards to the use of nuclear weapons, and it’s no wonder that Perry thinks that the chances of some catastrophe is a growing possibility.