The U.S. declaration of non-recognition of the annexation of Crimea by Russia in 2014 will be put in the office of the president of Ukraine, the presidential press service has said.

"My presence here in the U.S. and meeting in New York (meeting between the Ukrainian President and U.S. Special Representative for Ukraine Kurt Volker), where we had a great honor to receive the U.S. declaration on Crimea signed by Secretary Pompeo. It will be put in the presidential office of Ukraine, I promise you," Poroshenko said at the U.S. Coast Guard "Baltimore" base.

The document was made public by U.S. Department of State on behalf of Secretary of State Mike Pompeo in July this year, and during the 73rd session of the UN General Assembly, a copy was handed over to the head of the Ukrainian state.

"This is an extremely important document," the president said.

The president once again expressed his conviction that if leaders of the world continue to adhere to this position and support sanctions against Russia, Ukraine will be able to defeat the aggressor.

"If we keep up the pressure, Crimea will become an unbearable burden for Moscow, and the aggression will lose any sense for Kremlin. Russia started to pay the price for its irresponsible behavior, for illegal annexation of Crimea, aggression in the east of my country. Sanctions are working and it is necessary to reinforce them," he noted.

Poroshenko is also confident that upon returning of Ukrainian sovereignty to the Crimean peninsula, Russia will lose an opportunity to carry out aggression in other countries and destabilize the situation in the Black Sea region.

"With the liberation of Crimea, Russia will be out of a launching pad to project its power over Syria, to threaten the NATO flank in the Black Sea, to undermine the U.S.-led non-proliferation regime by refurbishing Soviet nuclear facilities in Crimea," the president stressed.