Millions of barrels of oil that would normally be preserve of oil refineries in Europe are instead heading to Asia as US sanctions on Russia revive one of the market’s great arbitrage trades.

Trade for March-loading Russian oil in top buyer Asia has stalled as a wide price gap between buyers and sellers emerged in China after costs for chartering tankers unaffected by U.S. sanctions jumped,

Russia has continued to send cargoes of crude oil to India on tankers that have been sanctioned by the US, Bloomberg reported on Tuesday. This situation presents a crucial test of Moscow’s ability to circumvent the stringent sanctions implemented by Washington earlier this month.

The rush to buy replacement cargoes for sanctioned Russian oil has pushed Middle Eastern crude prices to an unusual premium to the global benchmark.