Four-way talks call for end to Ukraine violence --- (Reuters) - The United States, Russia, Ukraine and European Union together called on Thursday for an immediate halt to violence in Ukraine, where Western powers believe Russia is fomenting a pro-Russian separatist movement. -- Washington immediately warned Moscow that it would face further sanctions if it did not carry out the agreement, reached in four-party crisis talks in Geneva. -- Russian President Vladimir Putin, speaking in Moscow, accused Ukraine's leaders of committing a "grave crime" by using the army to try to quell unrest in the east of the country, and did not rule out sending in Russian troops. --Putin said he hoped he would not need to take such a step, and that diplomacy could succeed in resolving the standoff, the worst crisis in East-West relations since the Cold War. -- The comments came hours after separatists attacked a Ukrainian national guard base overnight and Kiev said three of them were killed in the worst bloodshed yet in a 10-day pro-Russian uprising. -- Ukrainian, Russian and Western diplomats held emergency talks seeking to resolve a confrontation that has seen pro-Russian fighters seize official buildings across eastern Ukraine while Moscow masses tens of thousands of troops on the frontier. -- "All sides must refrain from any violence, intimidation or provocative actions," a joint statement issued after the Geneva talks said. -- "All illegal armed groups must be disarmed; all illegally seized buildings must be returned to legitimate owners; all illegally occupied streets, squares and other public places in Ukrainian cities and towns must be vacated," it added. - More, at: http://www.reuters.com/article/2014/04/17/us-ukraine-crisis-idUSBREA3A1B520140417