I look into Obama’s eyes and see K, G, and B.
It could even be worse than that.
It serves several purposes shows that he has a keen sense of humour but humour with real and solid meaning about it. People often take notice of things said with humour more than someone like Obama lecturing them as if they are school child. IMHO Obama comes over as all theory and no sunstance. When I was a school child in Britain we had a rule which I am certain since has been changed and not for the better. If you taught in school or college business studies or commerce to get a teaching qualification in this field you needed to have worked in it for at least 2 years so what you are passing on is real experience not just theory.
It also shows that McCain was aware that Russia at that time was not to be trusted and the comment trust and verify must go together.
And probably the most important if the media is to be believed and that he must distance himself from the current President this is just one example where he is saying my view of the former President now Prime Minister of Russia is different to George W Bush and therefore my dealings with Russia and my Secretary of State's and their department dealings will be handled differently.