Shells struck by the hundreds along the tense front lines in eastern Ukraine, drones monitoring a fragile cease-fire lost their way when the GPS signal they rely on was jammed, and then the cellphone network went dark.
In a sliver of land where pro-Russian separatists have battled for years against Ukrainian government forces, a group of international monitors tasked with keeping the peace reported more than 500 explosions in the the 24 hours ending Thursday midday, around four times as many as an average day over the past month.
