From CNN's Rich Barbieri
Three days before Christmas in 1975, President Gerald Ford signed a law creating the United States' first emergency stash of crude oil. The nation had been traumatized by an oil embargo a few years earlier.
At the time, OPEC, the cartel of oil-producing nations, had a stranglehold on the world's supply of crude. Today the United States is one of the world's largest producers and a major seller, not just a buyer, of oil.
But the United States still has its stash. The Strategic Petroleum Reserve contains 645 million barrels -- the world's largest backup oil supply.
On Sunday, US President Donald Trump authorized the use of oil from the emergency reserve following weekend attacks on Saudi Arabian oil facilities.
Read more on the strategic reserve, or SPR, here
From CNN's Rob McLean and Laura He
The attacks on key oil facilities in Saudi Arabia have disrupted about half of the kingdom's oil capacity, or 5% of the daily global oil supply.
That means 5.7 million barrels a day of crude oil and gas production have been affected, according to Saudi Energy Minister Prince Abdulaziz bin Salman.
Now oil prices are trading at their highest levels since May.
US oil futures were trading at more than $61 a barrel during Asia hours -- a spike of nearly 10%. Earlier, the price jumped as much as 15%. Futures of Brent crude, the global benchmark, traded at nearly $68 per barrel, an 11% increase.
Gasoline futures, meanwhile, were up about 9%.
"This is a big deal," said Tom Kloza, chief oil analyst for the Oil Price Information Service. "It is the biggest shock to the oil markets since [Hurricane] Katrina. And like Katrina it will likely haunt us for months, at least weeks."
Analysis by CNN's Tim Listersonos sonos One (Gen 2) - Voice Controlled Smart Speaker with Amazon Alexa Built-in - Black read more
The attack on the world's largest oil processing plant early Saturday morning is a dramatic escalation in the confrontation between Iran and Saudi Arabia -- even if the Iranians didn't fire the drones or missiles responsible.
Several projectiles struck the Abqaiq plant, starting a series of fires that quickly took out nearly half Saudi's oil production -- 5% of the global daily output -- and sparking fears about the security of the world's oil supplies.
It's unclear when Abqaiq, which is operated by Saudi giant Aramco, will be fully operational again.
Houthi rebels in Yemen claimed the attack, saying that 10 drones had targeted Abqaiq, as well as the Khurais oilfield. But attacks of this scale and accuracy would represent a sudden and remarkable increase in Houthi capabilities, and neither the United States nor Saudi Arabia is buying the claim.
The United States swiftly discounted the Houthi claim. Late Saturday, Secretary of State Mike Pompeo
: "Iran has now launched an unprecedented attack on the world's energy supply." And he added: "There is no evidence the attacks came from Yemen."
Tehran is behind nearly 100 attacks on Saudi Arabia while Rouhani and Zarif pretend to engage in diplomacy. Amid all the calls for de-escalation, Iran has now launched an unprecedented attack on the world’s energy supply. There is no evidence the attacks came from Yemen.— Secretary Pompeo (@SecPompeo) September 14, 2019
In response Iranian Foreign Minister Javad Zarif accused Pompeo of engaging in deception. He
: "Having failed at 'max pressure', @SecPompeo's turning to 'max deceit' US & its clients are stuck in Yemen because of illusion that weapon superiority will lead to military victory. Blaming Iran won't end disaster."
Having failed at "max pressure", @SecPompeo's turning to "max deceit"— Javad Zarif (@JZarif) September 15, 2019
US & its clients are stuck in Yemen because of illusion that weapon superiority will lead to military victory.
Blaming Iran won't end disaster. Accepting our April '15 proposal to end war & begin talks may.
The big question now, is where did this attack originate and who was behind it?
Read more of this analysis here.
the US has "reason to believe that we know" who is responsible for an attack on a Saudi Arabian oil field, adding that the country is "locked and loaded depending on verification" following the crippling strike.
Saudi Arabia oil supply was attacked. There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!— Donald J. Trump (@realDonaldTrump) September 15, 2019
Trump's tweet, which appeared to raise the specter of a US military response, served to ratchet up tensions in a region already on edge after Saturday's