As international crude futures remain stubbornly high near $110 a barrel, the market is increasingly polarised between those who see lower prices for physical cargoes as a red flag for oil bulls and those who think the weakness is a blip.North Sea Brent crude futures LCOc1, which help price at least two-thirds of the world's oil, have climbed as the situation in Ukraine raises tension between the West and Russia and as political turmoil cuts off supplies from Libya.But many physical traders say no real shortages have emerged, and a host of grades including Russia's main export crude and the streams that underpin Brent have diverged from futures, falling to multi-year discounts in the past week.The last time Forties crude from the North Sea traded at such a discount was just prior to a price crash of close to $35 a barrel in Brent futures that started in April 2012, and saw Brent fall to below $90 from more than $120.While few predict such a selloff this time, with prices holding in a narrow band of around $10 a barrel in 2014, some traders and analysts say the warning signs remain."Brent futures have run ahead of themselves due to geopolitics this spring," said VTB Capital analyst Andrey Kryuchenkov in London."But given no new disruptions, the physical markets are signalling they're well supplied, with crude differentials falling and refinery margins also in the dumps."In the opposing camp are those who see the market tightening later this year. They point to paper trading for physical cargoes and futures prices for later delivery that indicate oil may remain supported.Energy Aspects, a London-based consultancy, said last week the Organization of the Petroleum Exporting Countries (Opec) faces a "Herculean task" in the second half of 2014 keeping the market well supplied, confounding earlier expectations that the group would need to cut output due to the US shale revolution."Raising, not limiting, output is now the challenge for Opec," Energy Aspects said, pointing to lower-than-expected supplies from Libya and other countries.The consultancy says Opec needs to pump up to 31 million barrels per day (mbpd) in the last six months of this year, about 1 mbpd above current output.