Ukrainian President Petro Poroshenko is due to visit Washington on September 18 where he will address Congress and meet with U.S. President Barack Obama.
Poroshenko is making his first visit to Washington as Ukraine's president and is hoping to convince the U.S. government to provide further help for his country.
The United States has been supportive of Ukraine's government in its struggle with pro-Russian separatists in eastern Ukraine.
The United States, along with the European Union and others, have imposed a series of sanctions on Russia for the Kremlin's interference in Ukraine.
Poroshenko arrives in the United States after visiting Canada where Prime Minister Stephan Harper and the Canadian parliament vowed to continue their support for Poroshenko and his government.
Harper told Poroshenko Canada would never recognize Russia's annexation of Crimea or any other part of Ukraine.