U.S. president Donald Trump has blasted the oil producer group OPEC for driving oil prices to the highest level since 2014, saying that crude prices have been driven “artificially” high.

In one of his customary morning tweets, which comes the day after Brent crude oil hit a 3.5-year high of $74.75 a barrel, Trump said:

“Looks like OPEC is at it again. With record amounts of Oil all over the place, including the fully loaded ships at sea, Oil prices are artificially Very High! No good and will not be accepted!”

@realDonaldTrump

Brent crude oil, the international oil benchmark, turned slightly lower after the tweet, slipping 0.4 per cent on the day to $73.49 a barrel.

OPEC, which together with Russia has been cutting oil output by a combined 1.8 million barrels a day since the start of 2017, met on April 20 to review the impact of the output curbs so far.

Khalid al-Falih, the energy minister of Saudi Arabia and OPEC’s de facto leader, said prior to the U.S. president’s tweet that the world economy could handle higher oil prices.

That is despite OPEC’s own analysis suggesting they are close to having drawn down the vast majority of the oil inventory overhang that build up in 2014, when prices crashed from above $100 to below $30 due to excess supplies from the U.S. shale boom.

Trump’s tweet suggests oil prices may be a rare schism between his administration and Riyadh, which has tried to cultivate a much closer relationship with the president than it enjoyed with his predecessor, Barack Obama.

The New York Stock Exchange has been trying to win a listing of part of Saudi Arabia’s state oil company, Saudi Aramco—widely billed as the biggest in history—but recent indications have been Riyadh is wary of listing in the U.S. due to legal risks.

In November 2017, Trump tweeted: “Would very much appreciate Saudi Arabia doing their IPO of Aramco with the New York Stock Exchange.” It is “important to the United States!” he added.