The US on Monday did not rule out considering military options against Iran after a series of strikes on Houthi targets in Yemen. President Donald Trump earlier said he would hold Tehran responsible for every attack by the Yemeni rebels going forward.
US forces launched a wave of strikes at the weekend that hit dozens of targets, including "terrorist training sites", drone infrastructure, weapons factories and warehouses. Lt Gen Alexus Grynkewich, director of operations for the Joint Chiefs of Staff, said a "much broader set of targets" had been involved than in previous strikes.
"All options are on the table at this time" with regard to Iran, Pentagon spokesman Sean Parnell said during the first Department of Defence media briefing of the new administration.
Mr Trump said earlier on Monday that attacks by the Houthis, who have restarted a campaign against foreign ships crossing the Red Sea, were made possible by Iran.
"Any further attack or retaliation by the 'Houthis' will be met with great force, and there is no guarantee that that force will stop there," he said in a Truth Social post. Mr Trump said Tehran has dictated "every move, giving them the weapons, supplying them with money and highly sophisticated military equipment", as well as intelligence.
He said Iran will be held responsible for every future Houthi attack, "and those consequences will be dire".
Last week Mr Trump said he had written to Iranian leadership indicating he wanted a new nuclear deal. Iran has so far rebuffed his attempt at reopening negotiations.
While the strikes that began at the weekend were carried out "to restore freedom of navigation and re-establish American deterrence", Mr Parnell said this is not an "endless offensive".
"This is not about regime change in the Middle East," he said. "This is about putting American interests first." He said that the Houthis could "stop this tomorrow" if they promised to end their attacks.
Mr Parnell declined to answer directly whether there could eventually be US soldiers in Yemen.
Lt Gen Grynkewich said there were no "credible indications" that civilians had been killed in the latest strikes. The Houthis have claimed that more than 50 people, including several children, were killed and almost 100 injured.
"[It] might be a safe overall characterisation, dozens of military casualties so far, but I really can't characterise it much better than that at this point," Lt Gen Grynkewich said.
Local media in Yemen reported more US air strikes on Sanaa later on Monday.
During an earlier briefing, White House press secretary Karoline Leavitt blamed former president Joe Biden's administration for the Houthis' "piracy, violence and terrorism against American ships".
"But there's a new sheriff in town and his name is Donald Trump, and the world is officially on notice," Ms Leavitt told reporters at the White House. "Our message to Iran is you better take this President seriously. And I think the Houthis learnt the hard way this past weekend."
State Department spokeswoman Tammy Bruce said the more than 170 recorded attacks on American vessels is not something that should be managed. "It has to stop."
The US strikes are "meant to completely change the posture of the Houthis and, of course, in conjunction, in that dynamic with Iran", Ms Bruce said. "The days of pinprick responses, where we allow that [retaliatory strikes] to occur is over."
Iran told the UN Security Council on Monday that Mr Trump and other US officials had made "reckless and provocative statements", levelled "baseless accusations" and threatened the use of force against Tehran.
"Iran strongly and categorically rejects any accusation on the violation of relevant Security Council resolutions on arms embargoes in Yemen or involvement in any destabilising activities in the region," Iran's UN ambassador Amir Saeid Iravani wrote in a letter seen by The National.
“I wish to emphasise once more that Ansar Allah [the Houthis] and Yemeni authorities operate independently in their decision-making and actions, asserting that their operations are conducted in support of the people of Gaza and in response to violations of Yemen's sovereignty and territorial integrity."
Adla Massoud contributed to this report from the UN
