REUTERS

"I'm very concerned that now that Putin has got Donetsk, the east of Ukraine and Mariupol could be soon his next target," the senator said.

When asked about the possibility of attack on Kharkiv and Odesa, McCain said, "If Vladimir Putin thinks that he will get over the Ukraine crisis easily, without a price, then he will try to attack Odesa from the separatist part of Republic of Moldova. Russia has 1,400 soldiers, a so-called peace-keeping force, in Transnistria. He has put incredible pressure on the Baltic states. And besides, he has often said that the biggest disaster of the twentieth century was the collapse of the Soviet Union. He wants to restore the Russian empire."