When Paul Manafort, now Donald Trump's former campaign manager, arrived in Ukraine a decade ago to advise future president Viktor Yanukovych, he relied on one man to be his ears and voice as an interpreter.
That figure was a Russian citizen, Konstantin Kilimnik. But, say several people who used to work with him, it was an open secret among the Manafort team and at a previous employer that Mr Kilimnik, an army-trained linguist, had a background in Russian military intelligence.
