Oil prices ticked up in early trading on Wednesday after ending the previous session up more than 4% on worries that the Iran-Israel conflict could disrupt supplies.

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.

U.S. oil prices already jumped last week, which could cause prices at the pump to rise about 20 cents a gallon in the coming weeks, according to one estimate.