Satellite images issued by the United States have revealed the extent of the damage to two key Saudi oil facilities attacked by drones at the weekend.
The facilities came under attack at 04:00 (01:00 GMT) on Saturday.
Online videos showed explosions and large fires at the Abqaiq oil processing facility.
In a statement Saudi Arabia later announced the fires had been brought under control within hours, and no one had been killed or injured.
However the fires led to the interruption of an estimated 5.7 million barrels in global oil supplies, according to the statement.
What was the impact on the Abqaiq refinery?
Analysts have identified at least 17 hits.
An unnamed senior US official told ABC News the attacks on the Abqaiq refinery had involved a dozen cruise missiles and more than 20 drones.
A number of "spheroids" used to process crude oil were hit, apparently with pinpoint accuracy, and fires from blasts at other parts of the facility can also be seen.
Analyst Anthony Cordesman from the Center for Strategic and International Studies suggests the attacks could have been carried out using relatively unsophisticated drones operating as "weapons of mass effectiveness".
"It is virtually impossible to secure civilian facilities from a worker or visitor's capability to use a cell phone to get precise GPS coordinates, commercial satellite coverage is now very good, and there are many ways to produce the kind of image needed for terminal guidance from ordinary photos," he writes.
US officials say the images show damage consistent with coming from a west-north-west direction, not Houthi-controlled territory which lies to the south-west of the refinery.
Abqaiq is the world's largest oil processing facility, and about two-thirds of Saudi Arabia's total output is refined there.
Some seven million barrels of oil are processed each day.
The facility refines crude oil pumped from the Ghawar field, and is connected to both the Shaybah oil field through a 636-km (395-mile) pipeline and an export terminal in Yanbu.
What was the impact on the Khurais oilfield?
Infrastructure at the site, which is about 180km south-west of Abqaiq, also sustained damage.
Satellite images show two significant hits to two towers, with scorch marks visible on the ground from a significant fire.
The Khurais oil field is believed to produce more than one million barrels of crude oil a day.
It has estimated reserves of more than 20 billion barrels of oil, according to Saudi oil company Aramco.