It is a "shameful" fact that the United States is not able to provide Ukraine with weapons at a time when it is defending itself, McCain said, according to a report by U.S. broadcaster Voice of America.
McCain said he was the inability of the United States to act at crucial moments undermines the confidence of the international community.
"All over the world, including Eastern Europe, confidence in America is declining because of our inability to act in order to help the Ukrainian people suffering from Russian aggression," McCain said during the debate on the establishment of democracy in Eastern Europe.
He also said that the dismemberment of one state by another, unprecedented since the end of the Second World War, sets a trend that is obvious to the whole world, and especially to potential victims of Russia.
The senator said he would do everything possible to convince the Obama administration to provide Ukraine with weapons.
"Ukrainians are being annihilated. More than four thousand people have been killed, and it is shameful that the United States did not give the weapons with which those people could have defended themselves,” McCain said.