The end of that standoff seemed to signal the ultimate decline of the Soviet Union and the assent of its historical enemies. The fall of the Berlin Wall reunified Germany, its greatest European nemesis. Western Europe began a long and integrated economic expansion, which helped pull the Soviet Union’s former republics and satellite states into the Western fold. Hungary, Poland, the Czech Republic, Bulgaria, Estonia, Latvia, Lithuania and Romania all joined the Western military alliance of NATO, and it seemed as if Ukraine and Georgia might not be far behind. As President George H.W. Bush announced in his final State of the Union address in 1992, the United States had won the ideological struggle with the Soviet Union, leaving the U.S. as the “one sole and preeminent power” in the world.

This was a new world order in which Russia was increasingly diminished, searching for relevance and — with a smaller gross domestic product than even tiny Italy — increasingly relying on its military strength and nuclear arsenal to be heard. Using that military, Putin has spent the last few decades trying to re-prime the engine of the Cold War. He has aggressively increased military spending, updated Russia’s nuclear weaponry, sent thousands of Russian troops and mercenaries into Middle Eastern and African countries, occupied 20 percent of Georgia, and fomented separatist revolts in two provinces in Ukraine. In this context, the idea that Putin would invade its peaceful – but crucially non-aligned neighbor — seems much less far-fetched. Other former Soviet republics outside of the NATO alliance will certainly take notice, but the move signals dangerous times ahead for the whole Western world. Putin wants a Cold War do-over — in fact, he’s insisting on it. And he’s capable of wrecking the board if everyone doesn’t sit down and play.

KIT R. ROANE is a senior producer at Retro Report. This article first appeared in Retro Report’s free weekly education newsletter. Subscribe and receive lessons from history in your mailbox. Follow us on Twitter @RetroReport.