DUBAI, United Arab Emirates — A U.S. airstrike on an important oil port held by Yemen’s Houthi rebels killed more than 70 people and wounded many others, the Iranian-backed rebel group said Friday, marking a major escalation in the military campaign President Donald Trump launched against the faction last month.

The overnight strike on the Ras Isa port sent massive fireballs billowing skyward and turned tanker trucks into burning wrecks. It was the first American attack on a Houthi-controlled oil facility since the U.S. began its new bombing campaign. It also came just before the resumption of negotiations in Rome between the U.S. and Iran over Tehran’s rapidly advancing nuclear program, which Washington has linked to its Yemen campaign.

The U.S. is targeting the Houthis because of the group’s attacks on shipping in the Red Sea, a crucial global trade route, and on Israel. The Houthis are the last militant group in Iran’s self-described “Axis of Resistance” that is capable of regularly attacking Israel.

— The Associated Press