Ukrainian President Petro Poroshenko said on Thursday he would call on Russian President Vladimir Putin to rein in pro-Russian separatists when the two men meet next week and told the Kremlin chief he had "a strong country, a strong army" behind him.
Poroshenko spoke as government forces, despite taking heavy losses themselves, thrust deeper into rebel-held territory in Ukraine's Russian-speaking east and kept the separatists whom they have battled since April on the back foot.
The Ukrainian battlefield successes, after a faltering start in April when government forces were humiliated, have alarmed some Western governments who fear they could box Putin dangerously into a corner with no way out to save face.
German Chancellor Angela Merkel is scheduled to visit Kiev on Saturday to show her support for Poroshenko - but diplomats say she is also bearing a message that he should consider calling a ceasefire so as not to incur a backlash from Putin.
Poroshenko, who will oversee emotion-charged Independence Day celebrations on Sunday in Kiev in which veterans from the eastern front will take part in a military parade, talked tough on Thursday.
Indicating he too had a political image to defend at home, he told local journalists that in talks in Belarus's capital of Minsk next Tuesday, at which he will meet Putin, he would "call for the (rebel) fighters to be withdrawn from Ukraine".
"I am sure we will succeed in this," he said.
Kiev, supported by the United States and European allies, says Russia has orchestrated the separatists' rebellions in the Russian-speaking east, and armed them. Moscow denies this.
Steady drip of deaths
At the table in Minsk will also be Putin's partners in the Russian-led Customs Union, which beckoned unsuccessfully to Kiev to join, and a three-person delegation from the European Union, with which the new Kiev leadership sees Ukraine's future.