Brent crude surged to a two-month high amid escalating tension between Ukraine and Russia, the world’s largest oil producer. West Texas Intermediate rose to the most since September.

The European benchmark climbed as much as 3 percent, boosting its premium to WTI. Ukraine mobilized its army reserves as Russia seized control of the Black Sea region of Crimea. The U.S. is weighing sanctions against Moscow during the worst standoff between the West and Russia since the Cold War ended. WTI gained on speculation supplies at Cushing, Oklahoma, slid.

Brent for April settlement climbed $2.73, or 2.5 percent, to $111.80 a barrel at 11 a.m. New York time on the London-based ICE Futures Europe exchange. It rose to $112.39 earlier, the highest level since Dec. 30. Volume was double the 100-day average.

WTI for April delivery gained $2.51, or 2.4 percent, to $105.10 a barrel on the New York Mercantile Exchange. Earlier, it touched $105.22, the most since Sept. 20. Volume was 82 percent above the 100-day average. Brent’s premium over WTI was $6.70, up from $6.48 on Feb. 28, the narrowest level since October.