Joint actions of the United States and the European Union regarding Ukraine open development and modernization opportunities for the country, Ukrainian president-elect Petro Poroshenko said.

"Today well-coordinated actions of Washington and Brussels give us a chance for development and modernization," Poroshenko said at a meeting with U.S. Secretary of State John Kerry in Warsaw on Wednesday.

Poroshenko has thanked the U.S. people and government - "the U.S. has supported Ukraine's fight for freedom and democratic choice and this is extremely important for Ukraine," Poroshenko's press office told Interfax-Ukraine.

What happened in Ukraine is a wonderful example of courage and stamina for the entire world, Poroshenko's press office quoted Kerry as saying.

The Ukrainian people have shown what it is to be free and to choose future on their own, and Ukraine and the U.S. work in close cooperation, Kerry said.

On June 4 the 25th anniversary of the Communist era end is marked in Poland.