Ukraine's separatist bastion of Donetsk came under intense artillery fire Sunday, increasing strains on a two-month-old cease-fire deal between Ukrainian government forces and pro-Russian separatists.
European monitors in Ukraine say they are very concerned after seeing convoys of heavy weapons and tanks in separatist-controlled areas of Ukraine.
Swiss foreign minister and current chairman of the Organization for Security and Cooperation in Europe, Karl Erjave, said he is worried about a resurgence of violence. He urged all sides Saturday to do all in their power to further consolidate the cease-fire and stay away from acts that could lead to a new escalation.