In an apparent sign of infighting, one faction of pro-Russian insurgents in eastern Ukraine has reportedly evicted another faction from the regional administration building in Donetsk that has served as the separatists' headquarters.
Members of the so-called Vostok Battalion were reportedly upset after other rebels looted a supermarket near the Donetsk airport after a deadly battle on May 26.
The Vostok members seized the looted goods on May 29 and cleared away barricades outside building.
Western media reports said heavily armed fighters of the Vostok Battalion flooded into Donetsk last weekend. Many are believed to be from Chechnya and other areas in the Caucasus.
The U.S. State Department said on May 29 that U.S. Secretary of State John Kerry had raised concerns about foreign fighters entering Ukraine -- particularly Chechens -- with Russian Foreign Minister Sergei Lavrov.
Meanwhile, Kerry has said Russian troops massed on Ukraine's borders are moving back toward Moscow, but there are still "danger signs" – with evidence of trained Russians crossing into eastern Ukraine.
Kerry told PBS TV late on May 29 that evidence shows "trained personnel from Chechnya, trained in Russia" are infiltrating Ukraine "to stir things up, to engage in fighting."
The White House expressed concerns advanced weapons "from the outside" are being used by separatists after a Ukrainian helicopter was shot down on May 29 -- killing 14 soldiers, including an army general.
The remarks come after Ukraine's acting President Oleksandr Turchynov told parliament in Kyiv the helicopter was brought down by "a Russian portable antiaircraft missile."
In related news, Ukraine's acting defense minister said government forces had "completely cleared" pro-Russian rebels from parts of the separatist east and will press on with an offensive until peace and order have been restored.
Mykhaylo Koval was speaking to reporters in Kyiv on May 30, one day after 14 government troops, including a general, were killed when rebels shot down an army helicopter.
"Our armed forces have completed their assigned missions and completely cleared the southern and western parts of the Donetsk region and the northern part of the Luhansk region from the separatists," Koval said.
"Our given task is to bring peace and order to the region," he added.
Koval also repeated charges that Russia was carrying out "special operations" in eastern Ukraine.
He said Ukrainian forces would continue with military operations in border areas "until these regions begin to live normally, until there is peace."
Based on reporting by "The New York Times," dpa, AP, Reuters, and AFP