Oil futures edged higher Tuesday, on track for a third straight gain, as investors monitored rising Middle East tensions following U.S. attacks on Iran-backed Houthi rebels in Yemen over the weekend that drew threats of retaliation.

U.S. President Donald Trump said on Monday he would hold Iran responsible for any attacks carried out by the Houthi group that it backs in Yemen, as his administration expanded the biggest U.S. military operation in the Middle East since Trump returned to the White House.