Ukrainian President Petro Poroshenko said the crisis in his country would remain unresolved unless it received political, economic and military support from allies in Europe and beyond.
In an emotional plea at a security conference in Munich, Poroshenko held up the red passports of Russian soldiers he said had been found on Ukrainian territory, calling them the "best evidence" for the presence of foreign troops in his country.
"The Ukrainian question will remain unsolved as long as ... the people and politicians in Europe and the whole world don't provide solid practical support for Ukrainians' independence - politically, economically but also militarily," Poroshenko said.
"We are an independent nation and we have a right to defend our people," he added. "Over the course of the offensive we have proved to be responsible and we will not use the defensive equipment for attack."