Russian President Vladimir Putin ordered his military command to put nuclear-armed forces on high alert as Ukrainian fighters defending the city of Kharkiv said they had repelled an attack by invading Russian troops. #News #Reuters #UkraineCrisis #Russia #VladimirPutin #Ukraine Subscribe: http://smarturl.it/reuterssubscribe Reuters brings you the latest business, finance and breaking news video from around the globe. Our reputation for accuracy and impartiality is unparalleled. Get the latest news on: http://reuters.com/ Follow Reuters on Facebook: https://www.facebook.com/Reuters Follow Reuters on Twitter: https://twitter.com/Reuters Follow Reuters on Instagram: https://www.instagram.com/reuters/?hl=en