If you looked out from Europe in the 1990s, you could see sunshine on the horizon. With the end of the Cold War, NATO appeared to be on the road to irrelevancy. But the sunshine has faded. Russia's dismemberment of Ukraine should remind Americans and Europeans that European security, for which all of us paid a high price over the past hundred years, is not assured.

For Europe, the decade before 9/11 was hardly perfect. There were wars in the Balkans, and a civil war against Islamists in Algeria, across the Mediterranean. But Russia appeared to be democratizing. Turkey was moving toward Europe. The Israel-Palestinian peace process seemed to be working. Above all, Eastern Europe was secure and free.

Today, few of those hopes remain. Russia is an authoritarian menace. Turkey is unsure of its regional role. Palestinians have never unambiguously accepted Israel's right to exist as a Jewish state. The Arab Spring has toppled old autocrats, and replaced them with new ones, or with violent radicalism.

All of that is bad. But worse, Americans and Europeans alike are operating on the strategy born in the sunny 1990s. We act as though Europe has solved its security problem, as though it has stable and increasingly friendly borders. It does not.

NATO still exists, but a military alliance without a military is a contradiction in terms. European defense budgets have shrunk, reflecting the broader European public distaste for anything that reeks of hard power. Regrettably, most of the world feels differently.

And since the United States no longer has a single Army brigade permanently deployed in Europe, our own commitment has melted away. This is not because of the Obama administration's pivot to Asia. It's because of the gradual U.S. acceptance after 1989 that most of Europe's problems had been solved, and the European Union could be trusted to handle what was left.

The EU's approach was to employ soft power. North Africa would be slowly pushed toward reform by investment and diplomacy, Turkey would be strung along in negotiations about EU membership, and Ukraine would be pulled westward by support for civil society.

But in most cases, the EU's approach didn't work. Turkey tired of the EU's road to nowhere. North Africa didn't reform; it revolted. Ukraine was pulled toward Europe, but the EU's soft power strategy has been crushed by Russia's hard power hammer.

Russia's Vladimir Putin doesn't want to recreate the Soviet empire. He's learned the lesson of its fall: Don't occupy big places, like Poland, that hate your guts. His strategy is subtle: Use a Russian population, or create it by distributing passports, to manufacture grievances, then occupy a little chunk of territory and intimidate the rest. He still has vulnerable neighbors, including the Baltic republics.

This week, the crisis is in Ukraine. But Crimea looks likely to join Kaliningrad, Belarus, Transnistria, Nagorno-Karabakh, Georgia and Chechnya, all of which are either occupied in whole or in part by Russia, or are pseudo states recognized primarily by Russia and its cronies. These conflicts are frozen by Russian power, and too often ignored by the West, which encourages Putin to try again.

So the first job for the United States and Europe is not responding to the Ukrainian crisis, per se. It is to recognize that our strategy for securing Europe from the troubled periphery is broken. These threats do not stem only from Putin, though he creates more than his fair share. Contrary to our hopes, Europe still has a security problem, one that cannot be met by the EU. As in the Cold War, it will take American leadership in NATO, and American recommitment to the security of Europe.

 - Ted R. Bromund is a senior research fellow in the Heritage Foundation’s Margaret Thatcher Center for Freedom.