BEHIND THE CONFLICT:

Three factors led up to it:

First was a broken promise between a leader and his citizens. President Viktor Yanukovych had long promised to integrate Ukraine with the European Union by signing political and trade deals. In November, he refused to sign.

Second was a lingering Cold War-era fight between Russia and the West for influence over countries in Eastern Europe. While Europe and the United States have made a priority of fostering democracy in the former Soviet republics, the Kremlin sees an ulterior motive: the expansion of Western military and economic power. Perceiving a threat to its big military and economic interests in Ukraine, Russia exerted enormous pressure to scuttle the accords with the European Union.

Third was searing public outrage over the government's sometimes brutal response to the street protests that followed the president's about-face on ties with the European Union.

Timeline

In 2009, the European Union initiated an Eastern Partnership program to tighten ties with former Soviet republics, including Ukraine. Russia immediately registered alarm.

Russia had serious reasons for unease. Its Black Sea naval fleet is based in Ukraine, and pipelines in Ukraine carry Russian natural gas to customers in Europe. European officials dismissed Russia's concerns — a serious miscalculation given Russia's control over Ukraine's gas supply, and eastern Ukraine's dependence on Russia for business and trade.

Ukraine has long been caught between Europe and Russia, and Yanukovych, elected in 2010, had tried to strike a balance.

By January 2013, he said he intended to join Russia's Customs Union with other former Soviet Republics and sign political and economic agreements with the E.U.

Many Ukrainians, especially in the Western part of the country, saw the accords with Europe as symbolic of a larger push to improve their lives with much-needed reforms especially to the economy and the justice system. In March, Yanukovych published a decree directing the government to work toward signing the accords.

Street protests erupted in late November, when it became clear that Yanukovych would not move forward. At several junctures, the rallies seemed about to end, especially after Russia gave Yanukovych $15 billion in loans and natural gas discounts, only to be reignited by government missteps.

These included the beating by police of young protesters on Nov. 30 and the ramming through of new laws severely restricting free speech and assembly.

Tensions simmered until last week, when it seemed Parliament might squelch a deal to reverse constitutional changes that had expanded presidential powers earlier in Yanukovych's term. Demonstrators marched toward Parliament, setting off what quickly became the most violent clashes yet.

New York Times