The assault on oil facilities in Saudi Arabia this weekend has highlighted what analysts say is a rapidly evolving threat from Iranian-made weapons in the region, marking a potentially alarming shift toward precision strikes on critical infrastructure.
US officials believe that both cruise missiles and drones were used in the assault and that part of the operation, which was claimed by Yemen's Houthi rebels, was launched from Iranian territory, according to a US official. Tehran has denied involvement in the attack.
Iran maintains advanced missile and drone programs as part of its national defense strategy and has transferred some of those weapons and technology to allied forces in the region, including Houthi fighters in Yemen, US officials and weapons experts say. Tehran's drone and missile arsenals allow it to deter adversaries and support regional proxies, who can strike on Iran's behalf, analysts say.
"The same strategic logic that animates Iran's missile program is evident in its drone program: it enables Iran to operate from range, keep its territory safe and strike at far away targets," said Behnam Ben Taleblu, a senior fellow at the Foundation for Defense of Democracies. "Drones, missiles and rockets all feature into Iran's asymmetric security strategy and are relatively cheaper to produce."
The sophisticated nature of Saturday's assault, which targeted sensitive oil installations and took roughly half of Saudi Arabia's oil production offline, suggests that Iran's strategy has paid off, analysts say. A US official said that while part of the attack was launched from Iran, the Trump administration believes that Yemen's Houthis also contributed to the assault.
There were between 17 and 19 direct hits on Saudi oil facilities in Abqaiq and Khurais, some 500 miles from Yemen's border, the official said.
According to Justin Bronk, a research fellow at the London-based Royal United Services Institute (RUSI), there might be a strategic advantage to attack using drones and cruise missiles at the same time.
"The simultaneous arrival of warheads at different speeds and different heights can in theory "help with confusing and overwhelming defense systems," Bronk said.
A United Nations expert panel on Yemen concluded earlier this year that the Houthis were in possession of what are known as "suicide" or "kamikaze drones" - some of which are similar to Iranian models and with a long range - among other unmanned aerial vehicles used for reconnaissance.
The panel concluded that Houthi forces "retained access to the critical components, such as engines, guidance systems, from abroad that are necessary to assemble and deploy them."
A separate UN panel found that Iran had violated an arms embargo on Yemen by allowing Houthi rebels to access its weapons but did not say that Tehran had directly armed the group.
A contractor working for the Pentagon drone defenses said that small drones were unlikely to have traveled the distance from Yemen to the targets in Saudi Arabia. The contractor, who spoke on the condition of anonymity because he was not authorised to comment to the media, said that the aircraft would probably need wingspans of about six feet and could have been supplied by Iran.
But analysts also pointed to the alleged use of cruise missiles in the assault, which experts say are low-flying and far more difficult to detect.
Iran is believed to have developed what is known as a land-attack cruise missile based on the Soviet Kh-55 model and has also used Chinese anti-ship cruise missile technology to develop its own capabilities, experts say. Both Houthi rebels and Iran-backed Hezbollah in Lebanon have used anti-ship cruise missiles in recent years.
Such missiles are "harder to detect and defend against than drones," said Rawan Shaif, an investigator at Bellingcat, a website specialising in open-source intelligence. "They can be incredibly precise if the person who is guiding them knows what [they] are doing."
"This was a precision attack," she said of the assault on the Saudi oil facilities. "It was accurate to a 'T' if their aim was to hit" specific infrastructure at the site.