Washington (CNN) Secretary of State Mike Pompeo called the attack on Saudi oil facilities "an act of war" Wednesday, as President Donald Trump announced that he's ordered new sanctions on Tehran , the latest escalation in tensions between the two countries as US officials work to pin the blame on Iran.

Pompeo, who is in Saudi Arabia to consult with the kingdom's rulers on next steps, said, "We were blessed that there were no Americans killed in this attack, but anytime you have an act of war of this nature, there's always risk that that could happen. ... This is an attack of a scale we've just not seen before."

The top US diplomat said he is in the Middle East to build a coalition to deter Iran and signaled that the Trump administration will use the upcoming gathering of world leaders at the United Nations General Assembly to rally support for action against Tehran, which denies involvement in the Saudi attack.

'It's very easy to start'

"I'm confident that in New York we'll talk a lot about this and that the Saudis will too," Pompeo said. "It was on their soil. It was an act of war against them directly, and I'm confident that they will do that."

Pompeo's combative characterization of the attack came as Saudi Arabia presented pieces of weaponry it said tied Iran to the attack. Vice President Mike Pence has suggested a military retaliation is possible and some Republican lawmakers have said Tehran should get an "unequivocal" response.

But the President and US allies are sending conflicting signals.

Trump, who campaigned on getting the US out of foreign fights and has been critical of American involvement in the Iraq and Afghanistan wars, faces a battle for reelection that would be complicated by a new conflict. And Saudi officials have made clear to the White House that they do not want to be dragged into war either.

The President's sanctions announcement may signal his desire to avoid military conflict, analysts said, and in remarks to reporters in Los Angeles on Wednesday the President observed that it is easy to slip into a war.

"It's very easy to start," Trump said. "If we have to do something, we'll do it," adding that "we'll be adding some very significant sanctions against Iran."

Substitute, not prelude

Asked if he's looking at a military strike, the President said, "We'll see what happens." He noted that "there's the ultimate option and there are options less powerful than that ... the ultimate option meaning go in, war."

The US has yet to offer definitive proof that Iran conducted the attack, which has been claimed by Houthi rebels in Yemen. US officials have denied that's possible. Pompeo has gone so far as to say "it doesn't matter" whether the Houthis had the capability.

"As for how we know, the equipment used is unknown to be in the Houthi arsenal," Pompeo said, speaking to reporters off-camera before landing in Jeddah. "The intelligence community has high confidence that these were not weapons that would have been in the possession of the Houthis. That's probably the most important piece of information."

But a United Nations report says otherwise. In a January report by Yemen experts, the UN wrote about new, powerful Houthi drones capable of targeting Saudi Arabia.

"The most distinctive feature of the UAV-X is its significantly increased endurance and range," the report said, adding that it "may have a maximum range of between 1,200 km and 1,500 km, depending on wind conditions. It would give credence to the claims by the Houthis that they have the capability to hit targets such as Riyadh, Abu Dhabi and Dubai."

'It doesn't matter'

Pompeo, asked Wednesday why the Houthis couldn't be responsible for the attack, made clear that regardless of who actually it carried out, the US will hold Iran responsible.

"It doesn't matter," Pompeo answered. "This was an Iranian attack. It's not the case that you can subcontract out the devastation of five percent of the world's global energy supply and think that you can absolve yourself of responsibilities."

If the Houthis' claim turns out to be true "it doesn't change the fingerprints of the Ayatollah as having put at risk the global energy supply," Pompeo said.

Allies have taken a more cautious approach, with France and the United Nations sending investigators to the Kingdom and Japanese officials saying there is "a high possibility" the Houthis are indeed responsible.

Even Saudi Arabia has been more careful, linking Tehran to the attack, but not calling it an act of war or saying, as unnamed US officials have claimed, that Iran itself launched the attack from within its territory.

'That wasn't an attack on us'

The kingdom has made clear to the US that it does not want a war, sources familiar with Saudi-US discussions say.

When Saudi Defense Minister Prince Khalid bin Salman met with senior administration officials at the State Department, the Pentagon and the CIA in late August, he told them the Saudis wanted the US to maintain the economic squeeze on Iran, but asked the administration not take any action to start a war that the kingdom could get dragged into, according to two sources familiar with the discussions.

For his part, Trump has made clear he wants the Saudis to take the lead in any response since it was an attack on their soil. "We have to sit down with the Saudis and work something out," he told reporters on Tuesday. "That was an attack on Saudi Arabia, and that wasn't an attack on us."

And administration officials have said a decision on a response to the weekend attacks won't be made until Pompeo returns to Washington.

Kirsten Fontenrose, a former director of the Persian Gulf region on Trump's National Security Council, said that since the White House already knows where the Saudis stand, it may be planning to use the kingdom to give it cover for not taking military action. "This gives him [Trump] a way out to not push for kinetic action," Fontenrose said.

'Fall short'

Sen. Lindsey Graham, a South Carolina Republican and Trump ally, had criticized Trump's sanctions approach, saying Iran saw it as a "sign of weakness." On Wednesday Graham said he is "looking for a response that would restore deterrence and my belief is additional sanctions will fall short."

Trump said Wednesday that he and Graham "have a disagreement on that and there's plenty of time to do some dastardly things."

Earlier in the day, Trump tweeted that "I have just instructed the Secretary of the Treasury to substantially increase Sanctions on the country of Iran!"

Henry Rome, an Iran analyst at the Eurasia Group, said the tweet was "important because it appears to be Trump's effort to respond to the Iranian attack by sanctions measures and not by military steps."

"The way I look at it, this is the substitute for a military response, not the prelude to it," Rome said.

'Fairly marginal'

It wasn't immediately clear to whom or which sectors the new sanctions would apply. White House, Treasury and State Department spokespeople did not immediately offer details. Trump said Wednesday that an announcement would be made in the next 48 hours, without specifying whether it would be on sanctions or some other aspect.

The US has ratcheted up pressure on Iran after withdrawing last year from a multi-nation nuclear deal that constrained Iran's nuclear activity in return for an easing of economic sanctions.

The US "maximum pressure" policy has undermined the nuclear deal, creating tensions with European allies who are trying to keep the nuclear deal afloat. The Trump administration has sanctioned all key Iranian economic sectors, including aviation and shipping. And in May, it hit the lifeblood of Tehran's economy, sanctioning its energy exports.

The Trump administration has ratcheted sanctions up to the point that, Rome said, "at this point the US is scraping the bottom of the barrel with sanctions. After the decision to sanction Iranian oil in May, everything else is fairly marginal. When you look at effectiveness or impact, you're really out of significant sanction tools at this point."