The damage to world order from Vladimir Putin's invasion of Crimea will echo for years, but one of the biggest casualties deserves more attention: the cause of nuclear nonproliferation.
One lesson to the world of Russia's cost-free carve-up of Ukraine is that nations that abandon their nuclear arsenals do so at their own peril.
This story goes back to the end of the Cold War and the collapse of the Soviet Union. Russia's nuclear arsenal was spread among the former Soviet republics that had become independent nations. Ukraine had some 1,800 nuclear weapons, including short-range tactical weapons, air-launched cruise missiles and bombers.
Only Russia and the U.S. had more at the time, and Ukraine's arsenal was both modern and highly survivable in the event of a first strike.
The U.S. was rightly concerned that these warheads could end up in the wrong hands, and the Clinton administration made controlling them a foreign-policy priority.
The result was the 1994 Budapest Memorandum on Security Assurances in which Ukraine agreed to sign the Nuclear Nonproliferation Treaty and return its nuclear arsenal to Russia in exchange for security "assurances" by Russia, the U.S. and United Kingdom.
Those included promises to respect Ukraine's independence and sovereignty within its existing borders, as well as refraining from threatening or using force against Ukraine.
Contrast that with the current crisis. President Barack Obama and British Prime Minister David Cameron have blasted Russia for its clear violation of the Budapest accord, but those U.S. and U.K. assurances have been exposed as meaningless.
That lesson isn't lost on Ukraine, and it won't be lost on the rest of the world.
Had Kiev kept its weapons rather than giving them up in return for parchment promises, would Vladimir Putin have been so quick to invade Crimea two weeks ago? It's impossible to know, but it's likely it would have at least given him more pause.
Ukraine's fate is likely to make the world's nuclear rogues, such as Iran and North Korea, even less likely to give up their nuclear facilities or weapons.
As important, it is likely to make non-nuclear powers and even close U.S. allies wonder if they can still rely on America's security guarantees.
Perhaps the greatest irony is that President Obama has made nuclear nonproliferation one of his highest priorities.
Obama's legacy won't be new limits on the spread of nuclear weapons. Instead he'll be the president who presided over, and been a major cause of, a new era of global nuclear proliferation.
To underscore the point, next week Obama will travel to The Hague to preach the virtues of nonproliferation at his third global Nuclear Security Summit. Also expected: Vladimir Putin.
Copyright The Wall Street Journal. Reprinted with permission.