Ukrainian Prime Minister Arseniy Yatseniuk has called the United States a leader in defending Ukraine's independence and once again harshly criticized Russia.

Meeting with U.S. Senator John McCain on Saturday, Yatseniuk stressed that the U.S. is "an international leader in the fight for Ukraine's independence," the government press service said. "We really value this and hope for your support," he said.

Yatseniuk also commented on Russian President Vladimir Putin's recent statements on Ukraine and on Russia's role in the conflict in Donbas.

"Putin is an aggressor. Russia must pay a price for Crimea's illegal annexation and the invasion of Donetsk and Luhansk. Russia must act as a country that is a UN Security Council permanent member, not violate international law and not threaten the entire world," he said.

"We are different nations and different states," he added.

Yatseniuk and McCain discussed the U.S. Senate's act on supplying Ukraine with weapons and bilateral cooperation in the energy sector. The Ukrainian prime minister thanked foreign partners for their support in efforts "to make Ukraine more energy efficient and energy independent."