From the Guardian:

The murky events surrounding shady Russians stalking one another on the streets of Britain in recent months have outstripped the imagination of the most fevered thriller writers.

But after the horrifying murder of Alexander Litvinenko and the diplomatic furore which followed, new revelations of a second assassination conspiracy yesterday stretched credulity. Unfortunately, given the already-febrile state of relations between the United Kingdom and Russia, the latest story of a hitman apparently flying into the UK to target a victim at a luxury Mayfair hotel is far from a work of fiction. Senior Whitehall sources confirmed yesterday that the suspected assassin was intercepted in London last month before he could mount an attempt on the life of Boris Berezovsky, the Russian oligarch, who has infuriated President Putin with his open calls for insurrection in Moscow.