"People of Ukraine, this is your moment," John McCain told hundreds of thousands of cheering protesters on Independence Square at the weekend. "The free world is with you, America is with you, I am with you."

The exhortations from McCain to keep going with the fight to overthrow a government that, while increasingly erratic and repressive, was democratically elected, have raised eyebrows in Moscow, which has been batting away allegations that the Kremlin is interfering in the choices of a sovereign state by throwing the allegation right back at the west.

But the Kremlin is long used to the Arizona senator and former Republican presidential candidate being a thorn in its side, and indeed McCain has made it something of a personal mission to annoy Vladimir Putin. In 2006, McCain travelled to Georgia to meet one of Putin's biggest foes, then-president Mikheil Saakashvili, and went jet-skiing with him on the Black Sea.

After Putin took to the pages of the New York Times earlier this year to tell Americans they should not use military force in Syria, McCain penned a tit-for-tat response in Pravda. Headlined "Russia deserves better than Putin", the piece was a sustained diatribe against the Russian president: "He is not enhancing Russia's global reputation. He is destroying it. He has made her a friend to tyrants and an enemy to the oppressed, and untrusted by nations that seek to build a safer, more peaceful and prosperous world."

Putin, of course, is not someone who takes such jibes lying down. Back in 2011, when a huge and unexpected mood of protest swept Moscow, McCain fired off a tweet:

Putin was asked about the tweet during one of his televised phone-in sessions and let rip: "Mr McCain fought in Vietnam. I think that he has enough blood of peaceful citizens on his hands. It must be impossible for him to live without these disgusting scenes anymore … He was captured and they kept him not just in prison, but in a pit for several years. Anyone would go nuts."