Pompeo says US backs Saudi Arabia's 'right to defend itself'

US Secretary of State Mike Pompeo said Thursday that America backs Saudi Arabia's "right to defend itself" after a weekend attack targeted the heart of its oil industry, comments coming after he described the assault as an "act of war."

The attacks have reignited fears over a wider conflagration in the region, as tensions remain high over Iran's collapsing nuclear deal with world powers.

Pompeo's comments on Twitter came as he was in Jiddah, Saudi Arabia, after meeting with Crown Prince Mohammed bin Salman, the kingdom's defense minister.

The Saudis on Wednesday displayed missile and drone wreckage at a press conference, and cited other evidence they alleged shows the raid was "unquestionably sponsored by Iran."

Iran, which has denied involvement in the attack, warned the US it will retaliate immediately if it is targeted.

Pompeo wrote his tweet early Thursday after his meeting with Prince Mohammed over Saturday's drone and cruise missile attack on a crucial oil processing facility and oil field.

Yemen's Iranian-backed Houthi rebels have claimed the attack, but the US alleges Iran carried out the assault.

Pompeo called the attacks "unprecedented."

"The US stands with #SaudiArabia and supports its right to defend itself," Pompeo said.

"The Iranian regime's threatening behaviour will not be tolerated."

Pompeo did not elaborate. President Donald Trump has been noncommittal on whether he would order US military retaliation.

He separately said Wednesday he is moving to increase financial sanctions on Tehran over the attack, without elaborating.

Iran already is subject to a crushing American sanctions program targeting its crucial oil industry.

Pompeo was to next visit the United Arab Emirates to meet with Abu Dhabi's powerful crown prince, Sheikh Mohammed bin Zayed Al Nahyan.

The UAE is a close ally of Saudi Arabia and joined the kingdom in its war in Yemen against the Houthis.

The UAE announced Thursday it had joined a US-led coalition to protect waterways across the Mideast after an attack on Saudi oil installations.

The state-run WAM news agency quoted Salem al-Zaabi of the Emirati Foreign Ministry as saying the UAE joined the coalition to "ensure global energy security and the continued flow of energy supplies to the global economy."

Saudi Arabia joined the coalition on Wednesday. Australia, Bahrain and the United Kingdom also are taking part.

The US formed the coalition after attacks on oil tankers that American officials blame on Iran, as well as Iran's seizure of tankers in the region.

Iran denies being behind the tanker explosions, though the attacks came after Tehran threatened to stop oil exports from the Persian Gulf.

At the press conference Wednesday, the Saudis displayed broken and burned drones and pieces of a cruise missile that military spokesman Col. Turki Al-Malki identified as Iranian weapons collected after the attack.

He also played surveillance video that he said showed a drone coming in from the north.

Yemen is to the south of Saudi Arabia.

Eighteen drones and seven cruise missiles were launched in the assault, Al-Malki said, with three missiles failing to make their targets.

He said the cruise missiles had a range of 700 kilometers (435 miles), meaning they could not have been fired from inside Yemen. That opinion was shared by weapons experts who spoke to The Associated Press.

"This is the kind of weapon the Iranian regime and the Iranian IRGC are using against the civilian object and facilities infrastructure," Al-Malki said, referring to Iran's Revolutionary Guard.

He added: "This attack did not originate from Yemen, despite Iran's best effort to make it appear so."

Pompeo, who landed in Saudi Arabia shortly after the news conference, took a harder line, telling reporters: "The Saudis were the nation that was attacked. It was on their soil. It was an act of war against them directly."

Meanwhile, Iran sent a note to the US via Swiss diplomats Monday, reiterating that Tehran denies involvement in the aerial attack, the country's state-run IRNA news agency reported.

The Swiss have looked after American interests in Iran for decades.

"If any action takes place against Iran, the action will be faced by Iran's answer immediately," IRNA quoted the note as saying. It added that Iran's response wouldn't be limited to the source of the threat.

IRNA also reported that Iran's delegation to the annual UN General Assembly meeting has yet to receive the necessary US visas. Foreign Minister Mohammad Javad Zarif was to travel to New York on Friday, with Iranian President Hassan Rouhani following on Monday.

The UN meeting had been considered as an opportunity for direct talks between Rouhani and Trump.

Asked in Los Angeles whether Rouhani will come to New York, Trump said, "I really don't know. If it was up to me, I'd let them come."

"I would certainly not want to keep people out if they want to come," he said, referring to the United Nations.

As the host of the UN's headquarters, the US is required to offer world leaders and diplomats visas to attend meetings.

But as tensions have risen, the US has put increasing restrictions on Iranians like Zarif.