(Reuters) - Ukraine's rebels disavowed a new truce on Sunday hours after it took effect, saying it did not apply to the town where most fighting has taken place in recent weeks. Guns fell abruptly silent at midnight across much of eastern Ukraine in line with the ceasefire agreement, but the pro-Russian rebels announced that they would not observe the truce at Debaltseve, where Ukraine army forces have been encircled. "Of course we can open fire (on Debaltseve). It is our territory," Eduard Basurin, a senior rebel commander, told Reuters. "The territory is internal: ours. And internal is internal. But...