MOSCOW (AP) — An agreement struck by the U.S., the European Union, Russia and Ukraine has raised hopes for defusing the Ukrainian crisis, which has strained East-West ties to a degree unseen since the Cold War. After years of preparation for a partnership agreement with the 28-nation EU, Ukrainian President Viktor Yanukovych stepped back from the pact in late November in favor of pursuing closer ties with Russia. The move sparked protests in Kiev, on the Ukrainian capital's main square, which grew to hundreds of thousands of people after a brutal police crackdown. Well-organized groups of gunmen quickly overtook government offices and police stations in several cities in eastern Ukraine in April and then handed over control to pro-Russian demonstrators, who hoisted Russian flags on top of the buildings. The Ukrainian government has responded by sending in the army and police to uproot the protests, but it has been reluctant to use force, which could further fuel anger and trigger a Russian invasion. The negotiations produced a deal, which called on all parties to make sure groups are disarmed and free captured government buildings. Vagueness of the deal and mutual distrust mean that tensions will likely remain high in the run-up to Ukraine's presidential election set for May 25. Protesters in the east have shown no inclination to disarm or vacate the official buildings they seized, saying that they want radical nationalist groups in Kiev and Western Ukraine to act first.