Ukraine crisis: Surge in fighting ahead of peace talks
Fighting has surged in eastern Ukraine as government forces and pro-Russian rebels try to make gains before peace talks due to take place on Wednesday.
President Barack Obama called President Putin to warn that Russia will face greater costs if it continues its "aggressive actions" in Ukraine.
The Russian leader is due to meet those of Ukraine, France and Germany in the Belarusian capital Minsk.
Victoria Fritz reports.