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