Former US presidential candidate Senator John McCain said he was "disappointed" that the UK has ruled out military intervention in Ukraine and said European countries were "ignoring the lessons of history".
Asked if it was right to avoid such sanctions, McCain he told BBC Newsnight, "Of course not. I am not astonished, to be very frank with you. Disappointed but not astonished."
The situation was "the result of five years of naive relations with Russia, not the beginning of it", he continued.
"If the Europeans decide that the economic considerations are too important to impose severe sanctions on Vladimir Putin - which you get from the statement by Angela Merkel today - then they are ignoring the lessons of history," he added, comparing Putin's actions with those of Adolf Hitler in 1938.
Former US presidential candidate John McCain has called for some or all of the annual $1.5 billion (£1 billion) US aid package to Egypt to be withheld if a civilian government is not quickly restored in the country.
Most of the money goes to the military under an arrangement US leaders have honoured since Egypt's 1979 peace treaty with Israel.
The Republican Senator is among a group of Congressmen who believe the aid package should be adjusted because the latest military action in Egypt unseated a democratically elected president.
McCain said: "Regardless of what anyone thinks about Mohamed Morsi, he was elected by a majority of Egyptians last year.
"It is difficult for me to conclude that what happened was anything other than a coup in which the military played a decisive role.
"I do not want to suspend our critical assistance to Egypt, but I believe that is the right thing to do at this time".
Senator John McCain has told the US Senate that he does not believe President Barack Obama has made a final decision on arming Syrian rebels, "but he has made the decision that chemical weapons have been used".
He added: "I think it is obvious that they will be providing weapons. They need a no-fly zone."