Russia Masses Troops as Bodies Pile Up in Ukraine Poroshenko to sign critical EU pact By Kevin Spak, Newser Staff Posted Jun 19, 2014 12:37 PM CDT 17 comments Comments A pro-Russian fighter holds a gun during a handover of the bodies of Ukrainian troops killed in a plane shot down near Luhansk, at a check point in the village of Karlivka, June 18, 2014. (AP Photo/Evgeniy Maloletka) (Newser) – So much for that ceasefire. Intense fighting broke out in Eastern Ukraine today, with separatists telling Reuters that they were outgunned and taking heavy losses. "We beat off the first attack and destroyed one tank," one separatist said. "But it is difficult to take on 20 tanks." Government forces said the fighting broke out when rebels refused to lay down their weapons and observe the ceasefire. They estimate that 4,000 separatists were involved. Meanwhile, Russia has moved troops back to the Ukraine border, according to NATO. The developments came as President Petro Poroshenko announced that he would sign a pivotal association agreement with the EU on June 27, the BBC reports. It was ex-president Viktor Yanukovych's refusal to sign the deal that led to the unrest that deposed him and started the entire crisis in motion.