The Russian president has spoken explicitly about the worsening climate between Washington and Moscow, insisting that what the Obama administration wants is "diktat" rather than dialogue.

For all that, the US and Russia are still in contact over Syria. For all the harsh rhetoric and accusations, they both realise that they have a vital role to play in any eventual settlement of the Syrian drama.

Whatever its immediate strategic intentions, a permanent war in Syria doesn't benefit Moscow any more than Washington.

But without that basic level of trust and understanding between them, any dialogue rests upon shaky foundations. It was never supposed to be like this. The end of the Cold War was supposed to usher in a new era.

For a time Russia retreated from the world stage, but now it is back with a vengeance, eager to consolidate its position nearer home; to restore something of its former global role and to make up for perceived slights perpetrated by the West.

So where did it all go wrong? Why were Russia and the West unable to forge a different type of relationship? Who is to blame? Was it US over-reach and insensitivity, or Russia's nostalgia for Soviet greatness? Why have things now got so bad and is it correct to describe the present state of affairs as a "new Cold War"?

I am not going to try to give a comprehensive answer to all these questions - the intricacies of this story would require a book the length of Tolstoy's War and Peace! But I am going to try to throw out some pointers.