At Sunday's protest, Ukrainian opposition leader Vitali Klitschko rallied for a nationwide strike, asserting, "We will not step back until we are heard."
Rallies in favor of Ukrainian membership in the European Union began in November when Ukrainian President Viktor Yanukovych announced that Ukraine would not sign a pre-accession deal with the EU.
Since that decision, Yanukovych sent mixed signals in meetings with EU officials, giving the impression he was still interested in signing an agreement with the EU. However, in mid-December, Yanukovych announced he had agreed to a gas deal with Russia.
Protesters oppose Ukraine's economic alignment with Russia.