This editorial appeared in The Boston Globe

Of all the 40th anniversary commemorations of 1968 — a year with too much history for its own good — one of the saddest is Thursday's, marking the August morning when citizens of Czechoslovakia woke up to the sound of Soviet tanks clanking through their streets. It was the abrupt end of the Prague Spring, a brief period of liberalization that had proved too threatening to Soviet leader Leonid Brezhnev.

Inevitably, comparisons will be made to Russia's invasion this month of Georgia, in response to Georgia's assault on its own breakaway area of South Ossetia. While there is a superficial similarity in the two incursions, the motives behind them have little in common.

One measure of the difference can be found in the defense of Russia's Georgian invasion by former Soviet president Mikhail Gorbachev in The New York Times Wednesday. It was Gorbachev who said that Prague Spring leader Alexander Dubcek's "socialism with a human face" reforms were a model for his own "perestroika" in the 1980s.

Forty years ago, the invasion of Czechoslovakia was seen in the West as confirmation of the intransigence of Brezhnev and his Warsaw Pact allies toward any loosening of political and economic strictures. For Western young people who had taken to the streets that year to protest the Vietnam War, the Soviet invasion was a sobering reminder that Moscow was even less willing to tolerate dissent than Washington was.

By August, 1968 had already seen the Tet offensive in Vietnam, the decision by President Johnson not to seek re-election, the assassinations of Martin Luther King Jr. and Robert Kennedy, demonstrations in Mexico that would lead eventually to the slaughter of hundreds of students as the Mexico City Olympics were about to begin, and the collapse of the French government in the face of riots there. Just days after the Czech invasion, protesters and police clashed in the streets of Chicago at the Democratic National Convention.

Brezhnev's decision to send tanks into Czechoslovakia was heedless of the tectonic historic shifts that were occurring all over the globe. While much else might be changing in the world, the Soviet empire, taking a page from its suppression of Hungary's revolt in 1956, would not.

Or at least not for a couple of decades. In 1987, an official in Gorbachev's government was asked what the difference was between the Prague Spring and Gorbachev's reforms. His answer was 19 years. Dubcek is alleged to have said that you can crush the flowers but you can't stop the spring. The next time the flowers came up, it was in Moscow itself.