One thing President Trump has never lacked is a salesman's ability to hype a deal. And one of the deals Americans most covet is cheap gasoline — which means cheap oil.

Since hitting a recent peak of $84 a barrel in early October, oil has plunged around 20 percent in price. True to his nature, Trump has been quick to take credit: "If you look at oil prices, they've come down very substantially over the last couple of months," Trump said last week. "That's because of me."

That claim is, at best, debatable. But the president also has more a pressing problem: Saudi Arabia may be about to make oil much more expensive.

On Monday, the Saudi oil minister, Khalid al-Falih, said the kingdom would likely have to cut production by around one million barrels a day to keep the price from falling too low. While oil prices are still well below their early-October peak, the news sent them up a noticeable 1.3 percent on Monday. That brought them to just over $71 a barrel.

Saudi Arabia has tended to prefer oil prices around $80 a barrel recently — meaning yesterday's announcement signals a longer term tension with the Trump administration.

Saudi Arabia doesn't wield the same oil clout it used to. But it's still the second-biggest producer in the world, accounting for 12.7 percent of the global market. Interestingly, the world's biggest producer is now the United States, at 15.3 percent. But U.S. oil production is still more or less market-based. Saudi oil production is state-run and set according to the government’s preferences. On top of that, Saudi Arabia pumps out around a third of all the oil produced by the Organization of the Petroleum Exporting Countries (OPEC) — the international group of state-run oil producers.

In short, Saudi Arabia is still the biggest central planner in the oil industry and thus its most powerful decision maker. That's led to a weird passive-aggressive relationship with the U.S. president.

On the one hand, a big part of the president's foreign policy agenda was to scrap the nuclear weapons deal with Iran and re-impose sanctions on its oil exports. In an effort to cushion the effect on oil prices, the U.S. government has issued a number of waivers to various importers of Iranian oil. But Trump still needs the Saudis to produce more supply to compensate, and he often has to cajole them into doing so.

At the same time, Saudi Arabia's massive leverage makes it a default threat to the low oil prices that Trump touts so much. So the president views the the country accordingly: Last week, he went so far to claim that the oil price was coming down "because you have a monopoly called OPEC, and I don't like that monopoly."

Trump's bluster aside, Saudi Arabia has its own reasons for how much oil it does or doesn't pump.

The Saudi government relies heavily on its oil exports to finance itself. It has to walk a tightrope between keeping prices high enough to fill its coffers, but low enough that economies around the world don’t speed up their adoption of alternative energy sources.

In recent months, Saudi Arabia actually was ramping up oil production, along with Russia — the world's third biggest producer, whose oil industry is also state-run — and a number of OPEC countries. To no small extent, that was indeed because they were worried about sanctions on Iran. But the global oil market is also unpredictable, particularly thanks to the giant X-factor of American market-driven production. The most recent numbers suggested supply might wind up outpacing demand and driving the price too low. Hence the Saudis’ latest decision to throttle back.

"Production cuts might be necessary to stem this tide, so we expect a sharp change in tone between now and December meeting from Russia/OPEC indicating that they will cut output," Tamar Essner, the energy and utilities director at Nasdaq Corporate Solutions, told CNBC.

The final complication here is that this was a unilateral decision by Saudi Arabia. Russia and the other OPEC countries are not necessarily on the same page. In fact, tensions between them and Saudi Arabia have been growing for a while now.

Russia may have aligned its production decisions pretty closely with Saudi Arabia in recent years. But Russia's Energy Minister Alexander Novak said this weekend that he doesn't necessarily agree a coming supply glut is a major problem. "We need to look at the situation very carefully to see how it will develop so that we don't end up changing our course by 180 degrees every month," he added.

Meanwhile, Russia actually isn't a member of OPEC. And Saudi Arabia’s aforementioned cooperation with the Kremlin has aggravated the other nations in the group. Iran recently accused Saudi Arabia of doing the West's bidding. And multiple member nations are pushing for more freedom to run their oil production according to their own ends, without say-so from OPEC as a whole.

Then came the icing on that particular cake: In just the last few days, news broke that Saudi Arabia's premiere government-funded think tank had released a report contemplating a post-OPEC world.

Officially, it was just an exploration of hypotheticals. "Think tanks like to think. We won't discourage them of thinking," Al-Falih said. "We are asking them to consider all scenarios." In particular, experts widely agree that global oil demand is headed downward over the long haul, meaning Saudi Arabia will eventually have to adapt.

Still, in the midst of the Kingdom's cross-purposes with Trump, Russia, and the other OPEC members, it was a striking thing to contemplate. Especially since one of the scenarios the report envisioned was Saudi Arabia essentially becoming an OPEC of one: using its clout to unilaterally set terms for the entire global market, as much as its able.

Saudi Arabia, Russia, and the rest of OPEC will have their next big meeting in December. And perhaps the White House should hope they come to an accord. Because if going its own way becomes a habit for Saudi Arabia, Trump will find himself with even less control over one of his favorite talking points.