US Vice President Joseph Biden on Friday called Ukrainian President Viktor Yanukovych to express his disappointment at Kiev's move to suspend an association agreement and a free-trade pact with the European Union (EU). "As the vice president has told President Yanukovych before, it is our strong conviction that closer integration with Europe offers Ukraine a strategic opportunity to strengthen its democracy and return its economy to prosperity," the White House said in a statement. Ukraine suspended preparations on Thursday for signing an Association Agreement as well as Deep and Comprehensive Free Trade Agreement with the EU, as the 28-member bloc had been calling for the release of former Ukrainian Prime Minister Yulia Tymoshenko as a condition for signing the deals, a path to closer integration with the West. Kiev's intention to sign the long-negotiated agreements resulted in the deterioration of relations with its Eastern partners in recent months. Russia has threatened to impose trade restrictions if Ukraine signs the EU deals. In his phone talks with Yanukovych, Biden voiced "continued support of the United States for the Ukrainian people and their aspirations for European integration," the White House said.