Michael Gerson writes for the Washinton Post and his paragraph on Ukraine hits the nail on the head.

In the early 1990s, Ukraine briefly possessed the world’s third largest nuclear arsenal, including about 1,900 strategic weapons, an inheritance from the Soviet crackup. In exchange for security assurances — specifically, a Russian promise to “respect the independence and sovereignty and the existing borders of Ukraine” — the Ukrainian government turned over all its nuclear weapons to Russia in 1996. The Budapest Memorandum on Security Assurances is now a muddy scrap of paper stuck to Vladimir Putin’s boot. According to a Ukrainian legislator, there is now a “strong sentiment” in what remains of his country that this denuclearization was “a big mistake.”