'Washington expressed concern over the appearance of fighters from Russia's war-ravaged region of Chechnya among the insurgents.
The rebels for their part dismissed speculation of a rift in their ranks after a dozen local militants were evicted from their seat of power in Donetsk by a military brigade comprised largely of Chechens and other Russians from the volatile North Caucasus…
Ukraine's acting defence chief said his soldiers intended to push ahead with their so-called "anti-terrorist operation" despite demands by Moscow for all military activities to come to an immediate halt.
"We will continue working until this region starts working and leading a normal life," said Koval.
Ukraine's acting president Petro Poroshenko also vowed to punish those who used a sophisticated surface-to-air missile to shoot the MI-8 helicopter out of the Lugansk sky.
"We have to do everything we can to ensure no more Ukrainians die at the hands of terrorists and bandits. These criminal acts by the enemies of the Ukrainian people will not go unpunished," Mr Poroshenko told Ukrainian news agencies.'