CAIRO (AP) — The U.S. military announced Thursday that it is conducting the 13th night of strikes against Iran as clashes escalate over shipping routes. Earlier Yemen's Iran-backed Houthi rebels said they attacked two Saudi oil tankers in the Red Sea, potentially widening the Iran war as international oil topped $100 a barrel.
READ MORE: Yemen's Houthis attack Saudi tankers in the Red Sea, threatening to widen Iran war
U.S. Central Command said the latest attacks are designed to "further degrade Iran's ability to threaten civilian mariners and commercial vessels transiting regional waters" as the Americans push to regain control over the Strait of Hormuz and restore the flow of international shipping.
Meanwhile, the Houthis threatened to shut down another key trade route, with the world economy already reeling from Iran's closure of the Strait of Hormuz. The threat came as Iran and the U.S. have stepped up attacks as they vie for control of the strait, through which a fifth of the world's oil and gas transited in peacetime, setting off a scramble for alternative routes.
President Donald Trump threatened "major military punishment" against the Houthis if their attacks on ships continue.
"If they do this again, the U.S. will hold Iran responsible, in that the Houthis are a Surrogate and/or Proxy of Iran, and major military punishment will be inflicted upon Iran and, of course, the Houthis, themselves," Trump wrote on social media.
As the rhetoric escalated, so did the economic fallout. The price of Brent crude oil, the international standard, spiked more than 6% Thursday, to about $100 a barrel. That is the highest level since May, before the two sides reached a preliminary peace agreement last month that has since collapsed.
Prime Minister Ali al-Zaidi of Iraq, which has close ties to both the U.S. and Iran, was in Tehran on Thursday to call for peace and dialogue, and he promised not to allow Iraqi territory to be used for attacks on Iran, his office said. Al-Zaidi met with Trump earlier this month in Washington.
WATCH: Trump escalates threats, vows to target Iranian bridges and power plants
An Arab diplomat said Gulf states are increasingly pessimistic about finding an off-ramp. The diplomat, speaking on condition of anonymity due to the sensitivity of the situation, said regional countries like Pakistan and Turkey continue to push for de-escalation.
U.N. Secretary-General Antonio Guterres warned Thursday that the region is being pulled "into an ever-widening circle of confrontation" with one crisis feeding another and every escalation triggering the next.
"Diplomacy is the only way forward," Guterres told the U.N. Security Council. He called for Pakistan's efforts to mediate an end to the war to be strengthened.
Becatoros reported from Athens, Greece, and Binkley from Washington.