Oil prices have spiked amid fears that the Israel-Iran crisis could spiral into a broader conflict involving the United States. Brent North Sea Crude and West Texas Intermediate – the two most popular oil benchmarks – rose 4.4 percent and 4.3, respectively, on Tuesday as US President Donald Trump demanded “unconditional surrender” from Tehran.

Oil prices slipped $1 per barrel on Monday in volatile trading after reports that Iran is seeking an end to hostilities with Israel, raising the possibility of a truce and easing fears of a disruption to crude supplies from the region.

Oil prices resumed their upward climb and U.S. futures were lower early Tuesday after Israel’s military issued an evacuation warning to 330,000 people in Iran’s capital Tehran. Asian shares were mixed.