President Donald Trump says the U.S. doesn’t need energy from the Middle East.

But in reality, the U.S. economy remains deeply vulnerable to the gyrations of the world’s oil supply. And that means Trump’s own political fortunes could be exposed if Saudi Arabia cannot recover quickly from the Saturday drone attacks that shut down half of the kingdom’s oil production and sent global petroleum prices spiking.

After boasting on Twitter that the U.S. was “locked and loaded” to retaliate, Trump took to social media again on Monday with a series of reassuring claims on Twitter — including that the U.S. has “PLENTY OF OIL!”

U.S. and global oil inventories are ample and the dangers that the attacks could cause an oil shock are being softened, for now, by the bounty of the decade-old fracking boom. But the U.S. is far from being as self-reliant as Trump has implied in his tweets since Saturday’s drone attacks — and he inspired his own market jitters with his remark that the U.S. is “locked and loaded” for a response.

“Because we have done so well with Energy over the last few years (thank you, Mr. President!), we are a net Energy Exporter, & now the Number One Energy Producer in the World,” Trump tweeted early Monday. “We don’t need Middle Eastern Oil & Gas, & in fact have very few tankers there, but will help our Allies!”

U.S. energy production has indeed done well in recent years, thanks to the fracking boom that began during the George W. Bush administration and took off dramatically under the Obama administration. But the rest of Trump’s statement was either inaccurate or premature: The U.S. isn’t yet a net exporter of energy, mainly because of its huge appetite for energy. The International Energy Agency has said the U.S. could cross that threshold next year — but even if it happens, the price that U.S. energy consumers pay will still move up and down as the global markets do.

And U.S. refiners still import about 9 million barrels of oil per day, or about half the country’s total usage. About 10 percent of those imports come from the Persian Gulf countries, according the Department of Energy’s Energy Information Administration.

“U.S. drivers are about to find out at the pump that the shale revolution does not insulate us from shocks in the global oil market,” said Jason Bordoff, former Obama administration energy adviser who heads the Center on Global Energy Policy at Columbia University. “The U.S. being on the cusp of being a net-zero oil importer is a stunning change, but it’s still a global oil market.”

U.S. motorists could see about a 20 cents-a-gallon increase in prices at the pump if Monday’s spike in crude oil prices holds, said Andy Lipow, head of oil market analyst firm Lipow Oil Associates. And that may be just a taste of the price spikes to come, if the supply disruptions worsen or war breaks out with Iran.

“The oil market is pricing in an additional security risk” because of Saturday’s attacks, Lipow said. “I don’t think that security risk is going away. I think it’s going to increase, especially given the war of words going on now.”

Iranian-backed Houthi rebels have taken credit for the Saturday drone strike at the kingdom’s Abqaiq plant and its Khurais oil field, which disrupted an estimated 5.7 million barrels of the kingdom’s crude oil production per day, about 5 percent of the global supply. The Saudis were hoping to restore about a third of that lost capacity by end of day Monday, according to Energy Secretary Rick Perry, but restoring the rest could take weeks.

The disruption prompted oil prices to surge in trading overnight, posting their biggest jump since the 1991 before paring some of that strength by midday Monday. U.S. light, sweet crude oil futures were up nearly 12 percent at $61.48 per barrel, off the high of $63.34 a barrel hit early in the day, though that was still well below $100-a-barrel levels seen as recently as 2014.

Energy experts said oil prices have been relatively low in recent weeks amid expectation of a global economic slowdown and even the current rally hasn’t lifted them high enough to cause real pain yet for U.S. consumers. Still, if the Saudi output remains offline for an extended period of time — or more attacks follow — the effect on prices is likely to grow.

In a concrete step to calm nerves, Trump said Sunday that he had authorized the release of oil from the U.S. Strategic Petroleum Reserve, a network of storage sites that hold more than 600 million barrels, equivalent to about two months’ domestic supply. But Perry walked that back Monday, saying that it was too early to release oil into the market, an emergency measure the U.S. last did in 2011, according to DOE.

“I think the president was spot on when he said the SPR would be available if needed,” Perry told CNBC. “I think we are yet a little premature on making any comments on actions now whether the SPR is going to be needed, until we get a real handle on the length of time the facility is going to be down.”

Any sustained surge in oil prices could create awkward questions about some of Trump’s energy policies, including his plan to roll back automobile fuel efficiency standards — in essence allowing more gasoline-guzzling cars and trucks onto the highways. That move would keep U.S. gasoline consumption about 500,000 barrels a day higher than it would be under the Obama administration’s fuel efficiency rule.

The current low oil prices appear to be concealing that political risk. But should oil infrastructure in Saudi Arabia, Kuwait or the United Arab Emirates face another attack, the resulting rise in oil prices will caused American motorists to take another look at Trump’s fuel efficiency moves, said Amy Myers Jaffe, director of the Council on Foreign Relations’ program on energy security and climate change.

“It could make that a really unpopular policy in an election year,” Jaffe said. “Right now we have a limited problem [with oil prices], but it could become a bigger problem.”

On the other hand, some Democratic presidential candidates such as Sens. Bernie Sanders and Elizabeth Warren could face vulnerabilities of their own after calling for a nationwide ban on fracking — the technology that has helped cushion the blow of the Saudi disruption.

For all of the weekend’s jitters, global energy markets have not yet priced-in the possibility of a war with Iran, even though Secretary of State Mike Pompeo blamed the country for the attack. One reason: Many oil analysts believe that Trump will not proceed with any large-scale confrontation, said Pavel Molchanov, oil analyst at Raymond James in Houston.

Anaylysts are still debating the chances that the White House calls for large-scale military action. But the White House had already indicated its wariness about taking too hard a line after the departure last week of hawkish national security adviser John Bolton, Molchanov said.

“The consensus view is that this administration does not want to have the massive economic dislocation that could result from an actual military confrontation, including, for example, a blockade of the Strait of Hormuz,” Molchanov said. “Bolton’s dismissal last week points in that same direction.”