Ukrainian President Petro Poroshenko has said he is counting on the new U.S. administration of President-elect Trump to assist Ukraine in its battle against Russian aggression.

"I think President-elect Trump must now muster [U.S.] capabilities and use everything in his power to support us in our battle for independence and democracy," Poroshenko said in an interview with the Bloomberg news agency during his visit to Davos, Switzerland.

He said a positive outcome would be the withdrawal of Russian armed forces from Ukraine and the return of Crimea, which was annexed by Russia in early 2014.

"At least I think there is a window of opportunity for the time being. In this context, Americans support this idea," Poroshenko said.

"We are doing everything we can, everything in our power, to motivate Russia to take its hands off our territory," Ukraine's head of state said.

The president said Kyiv is using political and diplomatic means, but is simultaneously building a strong army, implementing reforms domestically and using legal instruments, including claims to international courts.