Traders and crude market analysts are baffled by a ship-to-ship (STS) transfer of a Rosneft crude cargo offshore India without any attempt to conceal the origin of the oil, as the U.S. sanctions on Russia’s top oil producers and exporters have upended India’s crude purchases in recent weeks. Earlier this week the Fortis tanker, sanctioned by the UK and the EU, took about 720,000 barrels of Russia’s Urals crude from another sanctioned vessel, the Ailana, off the coast of Mumbai, according to tanker-tracking data compiled…