The EU says it is putting on hold work on a key trade agreement with Ukraine, saying the government's arguments have "no grounds in reality". Protesters have taken to the streets in support of the agreement, which was rejected by the government.
United States Senator John McCain has told protesters rallying for Ukraine's integration within the European Union that "Ukraine will make Europe better and Europe will make Ukraine better".
"We are here to support your just cause, the sovereign right of Ukraine to determine its own destiny freely and independently," Senator McCain said.
"The destiny you seek lies in Europe."
There is an urgent need for de-escalation in Ukraine as President Yanukovich tries to calm a country bitterly divided over years of history.
Ukraine's political and economic landscape is stuck between old Soviet masters in Russia and the democratising ideals offered by the EU.