Ukraine PM: 'Russia Wants World War III' Arseniy Yatsenyuk amps up rhetoric By Kevin Spak, Newser Staff Posted Apr 25, 2014 1:25 PM CDT 58 comments Comments Ukrainian Prime Minister Arseniy Yatsenyuk speaks to lawmakers during a session at the Ukrainian parliament in Kiev, Ukraine, Friday, April 18, 2014. (AP Photo/Sergei Chuzavkov) (Newser) – Russia's incursion into the Ukraine could easily spill past its borders, Prime Minister Arseniy Yatsenyuk said today, amping up his rhetoric against the Kremlin. "Attempts at military conflict in Ukraine will lead to a military conflict in Europe," he warned, in a TV appearance and web statement, according to USA Today. He said Russia planned to initiate just such a conflict, after first undermining Ukraine's elections and destabilizing it politically. "The world hasn’t forgotten the World War II, but Russia already wants to start World War III." Meanwhile: President Oleksander Turchynov's chief of staff said that the military operation on Slovyansk had entered its "second stage," with troops encircling the city and cutting off all supplies, CNN reports. He also said that Russia had refused to explain the presence of troops on the border. A bus with 13 people on board—including foreign observers—was stopped outside Slovyansk, and its passengers detained. It's unclear who did the detaining. New York Times reporters in the city say Ukrainian infantry units are patrolling nearby farmland, and well-armed Ukrainian forces are positioned on the road to Izyum north of Slovyansk. Barack Obama backed up John Kerry's sanctions threat in a news conference in South Korea today. "We will continue to keep some arrows in our quiver," he said, promising that more punitive measures were "ready to go."