CAMBRIDGE, Mass. — On Nov. 21, summoned by a Facebook post by a journalist named Mustafa Nayem, more than 1,500 Ukrainians showed up in Independence Square in Kiev to protest their government’s decision to “pause” preparations for signing an association agreement with the European Union. The next day, more crowds gathered, in Kiev and other cities. Soon, the protesters numbered over 100,000.

This month is the ninth anniversary of the “Orange Revolution,” which forced the authorities to annul the results of a contested presidential runoff and hold a revote. But in a country that has been largely apathetic for nearly a decade, no one could have expected such a strong reaction to a decision that would not even guarantee Ukraine’s full membership in the European Union — not even in the future.

The government’s arguments against the agreement seemed reasonable enough: Russia was pressuring Ukraine to join a Russian-led customs union, and the country could not risk losing access to the Russian market, which would surely happen if it signed a free-trade deal with the European Union.

Yet Ukrainians, despite poverty and cynicism, care. President Viktor Yanukovich had raised hopes for integration, and Parliament had passed measures that would move Ukraine toward compliance with the terms necessary to sign an association agreement and form a free trade zone with the European Union. Polls showed that a strong majority of Ukrainians supported integration with Europe, even in the East, the region most oriented toward Russia.