JEDDAH, Saudi Arabia (Reuters) - The United States wants to build a coalition of European and Arab partners to deter Iran after an attack on Saudi Arabia that Secretary of State Mike Pompeo described on Wednesday as “an act of war” against the world’s top oil exporter.

“This is an attack of a scale we’ve just not seen before,” Pompeo told reporters travelling with him before landing in the Saudi city of Jeddah for talks with Crown Prince Mohammed bin Salman. “The Saudis were the nation that were attacked. It was on their soil. It was an act of war against them directly.”

The top U.S. diplomat, who will also visit the United Arab Emirates, said drone and cruise missile strikes on two Saudi oil installations on Saturday had not come from Yemen’s Iran-aligned Houthi group, which has claimed responsibility.

Riyadh has said Iranian weapons were used and it is investigating the launch point. Iran has denied any involvement in the assault that initially halved Saudi Arabia’s oil production.

Pompeo said flight patterns suggested the attack did not come from the south, which is the direction of Yemen, and that the U.S. intelligence community has “high confidence” the weapons used were not in the Houthis’ arsenal.

“Were that true -- it’s not, but were that true -- it doesn’t change the fingerprints of the Ayatollah as having put at risk the global energy supply,” he said, referring to Iran’s Supreme Leader Ayatollah Ali Khamenei.

“We also know that these are systems that the Iranians have not deployed anyplace else, that they have not deployed outside of the country, to the best of our knowledge,” he added. “We’ve seen no evidence that it’s come from Iraq. It could well have travelled over Kuwait, we’ve not seen that either.”

Reuters reported on Tuesday that the United States believes the attacks originated in southwestern Iran, according to U.S. officials