WASHINGTON, Aug. 6 (Xinhua) -- U.S. Vice President Joe Biden and Ukrainian President Petro Poroshenko on Wednesday expressed concern over an alleged ongoing Russian military buildup on Ukraine's border.
In a telephone talk, the two leaders also voiced their concern over Russia's statements suggesting a role for Russian "peacekeepers" in Ukraine and Russia's continuing transfer of weapons to Russian "proxies" in Ukraine, the White House said.
Russia on Monday started a week-long military drill involving over 100 bombers and fighter jets with the purpose of improving coordination between its aviation and air defense systems.
Over the phone, Poroshenko told Biden about Russia's direct involvement in the conflict as a result of incidents of ordnance fired at Ukrainian military forces from the Russian side of the border, the White House said in a statement.
Poroshenko reaffirmed his commitment to avoiding civilian casualties and minimizing collateral damage while trying to restore law and order in eastern Ukraine, the statement said.
The two leaders also discussed the possibilities for a diplomatic resolution to the crisis, it added.
At a UN Security Council meeting on Tuesday, Russia's UN ambassador, Vitaly Churkin, said shells fired by Ukrainian armed forces "continue to fall into Russia" and "there were about 20 such cases on Aug. 3."
He said his country stands ready to help ease the humanitarian situation in eastern Ukraine.