On Nov. 9, 1989, the Berlin Wall finally cracked. East and West Germans, together, began to tear down the wall in a peaceful act that came to symbolize the end of the Cold War. No one predicted it. Amazingly, no one stopped it, even those who had the most to lose—like the Soviets and their pioneering leader Mikhail Gorbachev. Two years later, the Soviet Union was gone.

Back then, hopes were high for a huge “peace dividend” that would take U.S. defense dollars formerly aimed at the Soviet threat and spend them on domestic needs. Others expected that nuclear arsenals would decline to zero as the arms race shifted into reverse. With Soviet ideology and society in tatters and the Warsaw Pact defunct, what were the weapons for anymore? Gorbachev said in December 1991, as the hammer and sickle was lowered for the last time from the Kremlin, “The threat of world war is no more.” Weeks later, President George H.W. Bush offered a more triumphalist, and in retrospect troubling, take: “The biggest thing that has happened in the world in my life, in our lives, is this: By the grace of God, America won the Cold War.”

Fast forward to today. U.S.-Russian relations are at an all-time low, and defense budgets are at all-time highs. The United States and Russia are undermining nuclear arms control treaties such as INF and New START, and spending trillions of dollars to rebuild their strategic arsenals. We are back in a nuclear arms race.

What happened? How did we manage to squander such a rare opportunity to build a new partnership with Moscow?

The tragic collapse of U.S.-Russian relations over the last 30 years has many causes, but one stands out for breaking a fragile trust and steering a potentially cooperative relationship back to competition. On this crucial issue, the United States refused to lend a hand to a struggling Russia, and instead kicked it when it was down.

What was this issue? The expansion of NATO.

In 1996, the Clinton administration decided to invite former Soviet allies Poland, Hungary, and the Czech Republic into NATO, the military alliance formed to oppose the Soviet Union. To Russia, which had just peacefully dismantled an empire built at least in part to prevent yet another ruinous foreign invasion, this would be an encroachment into territory it still viewed as a security buffer of existential importance. Defense Secretary William Perry, who had been slowly building a positive relationship with Moscow, tried to stop the process from the inside but could not. The political momentum was too strong. President Bill Clinton and Vice President Al Gore believed they could manage the problems with Russia. They were wrong.

Many at the time knew this was an historic blunder. In an open letter to President Clinton, more than 40 foreign policy experts —Bill Bradley, Sam Nunn, Gary Hart, Paul Nitze, Robert McNamara, and more — decried NATO expansion as expensive and unnecessary. No one listened.

As Russia expert George Kennan said in 1998, “I think [NATO expansion] is the beginning of a new Cold War. I think the Russians will gradually react quite adversely and it will affect their policies. I think it is a tragic mistake.”

“Don't people understand?” lamented Kennan, author of the Cold War doctrine of containment. “Our differences in the Cold War were with the Soviet Communist regime. And now we are turning our backs on the very people who mounted the greatest bloodless revolution in history to remove that Soviet regime.”

As predicted, Russia saw NATO expansion as a threat. When the alliance added the Baltic states in 2004, Moscow viewed it as marching that threat up to its border. With a frightful lack of forethought, the United States and NATO essentially acted as if Moscow’s concerns did not matter.

When President Obama came into office in 2009, he announced he would try to repair the damage and seek to “press the reset button” on U.S.-Russian relations. For a while it seemed to work, and President Dmitri Medvedev (who took over temporarily from President Vladimir Putin) had a more positive attitude toward Washington. During this brief opening, the New START treaty was signed in 2010. But then Medvedev stepped down to make way for Putin’s return.

After Putin’s re-election in 2012, U.S.-Russian relations went into free-fall. There were large demonstrations in Russia against Putin after the election, and he apparently believed they were organized and financed by the United States. When the new U.S. ambassador, Mike McFaul, arrived, some Moscow media reported that he was sent by Obama to help overthrow Putin.

By this time, Putin had decided to give up on the West. Instead, he would “make Russia great again,” an appeal to Russian nationalism built on rhetoric that was anti-foreigners, but mostly anti-U.S. In 2014, Sochi hosted the Winter Olympics, an impressive event meant to show the world that Russia was back. (Russian athletes were discovered to have used illegal drugs, and were barred from the next Winter Games in South Korea.) Soon after, Russia began military operations in Crimea, and then moved troops into eastern Ukraine. As if to demonstrate its hostility and independence to Americans, the Russian government interfered in the 2016 U.S. presidential elections.

So here we are. What started as a promising courtship, with great potential to improve global security and reduce nuclear dangers, has now crashed into a wall. NATO expansion, compounded by NATO’s anti-missile interceptor deployments on Russia’s doorstep, played a key role. Together they were seen by Moscow as signs of encroachment and disrespect for Russia and its interests.

Gorbachev, now 88, said in a recent interview, "As long as weapons of mass destruction exist, nuclear weapons, the danger is colossal. All nations should declare, all nations, nuclear weapons must be destroyed. To save ourselves and our planet."

Presidents Trump and Putin are now moving in the opposite direction, rebuilding arsenals while destroying international controls. As we welcome the 30th anniversary of the Cold War’s demise, we must learn from the mistakes that squandered such a golden opportunity. We must own the fact that after taming the Russian bear, we found it more convenient to have an adversary. Despite Bush’s triumphalism, the United States did not win the Cold War. We both lost, and until we choose a different path we will keep losing.

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