At the heart of the crisis shaking Ukraine are deep economic problems and the country should seek help from the International Monetary Fund, US Treasury Secretary Jacob Lew said Wednesday. In December, Russia promised a $15 billion bailout loan to Ukraine and a reduction by a third of the future price of Russian natural gas deliveries as Kiev teetered on the brink of bankruptcy. "At the core, they have an economic crisis and they are going to need to deal with it," Lew told a conference hosted by the World Affairs Council in San Francisco. "And the mechanism that's best for Ukraine to deal with it would be to come to the IMF and to have a package where they put in place economic reforms, where they get the support that they need, in exchange for the steps to fix the economy." The Russian bailout was promised to Ukraine after President Viktor Yanukovych rejected a European Union trade and political pact in favor of closer ties with Russia, a move that triggered widespread protests and led to the resignation of the prime minister. Moscow has effectively frozen the much-needed loan after paying just one $3 billion instalment, as it waits for the appointment of a new government in the struggling country.