U.S. President Donald Trump told world leaders at the U.N. General Assembly in New York City on Sept. 25 that the Organization of Petroleum Exporting Countries (OPEC) is “unfairly” manipulating oil prices. Trump’s criticism came just as crude oil prices reached a four-year high of $82.01 a barrel on September 25. This year alone, the cost of a barrel of oil has increased more than 20 percent.

The President’s criticism, however, is only partially accurate. Several factors in addition to OPEC’s ability to limit production also affect oil prices. These include the U.S.’s decision to re-impose sanctions on Iran; the political, economic, and security crises in Venezuela and Libya; trade tensions between China and the U.S.; and increased U.S. production of shale oil.

President Trump announced during his speech to the U.N. General Assembly, “OPEC and OPEC nations are, as usual, ripping off the rest of the world, and I don’t like it . . . . We defend many of these nations for nothing, and then they take advantage of us by giving us high oil prices. Not good.” He had tweeted a similar statement on September 20, calling on OPEC to lower prices immediately.

The oil cartel, however, ignored Trump’s demand. During the OPEC World Oil Outlook in Algiers on Sunday, September 23, OPEC ministers and allied producers did not agree to an increase in production,  suggesting that prices are likely to continue to rise. The Saudi Energy Minister Khalid al-Falih stated at the meeting, in response to Trump’s comments: “I do not influence prices.”

Trump blames OPEC for rising oil prices because it has been limiting oil production since January, 2017. On November 30, 2016, OPEC announced that it would reduce output by 1.2 million barrels per day by January, 2017. It did so in an effort to push up oil prices to compensate for the slump in profits over the previous two years. Its total revenue in 2016 was $341 billion, compared to $753 billion in 2014. In June of this year, however, OPEC and its allies decided to ramp up output by an estimated 1 million barrels per day, to compensate for shrinking the oil supply more than they had intended.

Trump’s decision to re-impose sanctions on Iran have driven oil prices up by around $10 per barrel since mid-March. The next round of sanctions, set for November, are likely to push oil prices higher by curbing the world’s supply of oil. The U.S. government has ordered China, India, and Turkey to stop all imports of Iranian oil by November, though it is unlikely that countries like China will comply. On September 24, Iranian President Hassan Rouhani retorted, “[T]he US is not capable of bringing our oil exports to zero. This is an empty promise and it’s a threat that is empty of credibility. Perhaps on this path we will sustain certain pressures but certainly the United States will not reach its objective.”

The political and economic crises in Venezuela and Libya have also hurt the world’s supply in oil and contributed to the rise in prices earlier this year. Venezuela’s production of oil slipped by almost 50 percent from over 2.2 million barrels per day in 2016 to 1.54 million barrels by February 2018. As the crisis drags on, the fall in production does not appear likely to improve in the near future.

Libyan oil production has also been affected since the country descended into civil war in 2011. Libya’s National Oil Corporation (NOC) claims that oil production is at its highest levels since 2013 and will continue to rise. NOC Chairman Mustafa Sanalla stated in September that output was recently at 1.278 million barrels a day and could rise by hundreds of thousands of barrels if security improves. However, that remains a big if, as rival militias in the vicinity of Libyan oil fields continue to clash with one another. In short, the Libyan oil supply should be viewed as a wild card.

Supply has been offset somewhat, though, by an increase in U.S. shale production, which nearly doubled from 5.7 million barrels per day in 2011 to 9.2 million mbd in 2014. The U.S. Energy Information Administration (EIA) predicts that oil output from shale formations in U.S. will reach 9.6 mbd in 2018. At this rate, the U.S. is on track to become a net energy exporter by 2022, according to the EIA. The production of alternatives to oil, like ethanol, has also increased since 2015.

OPEC’s decision not to increase production may be due, in part, to an anticipated decline in Chinese demand for oil. China’s demand is affected by the escalating trade spat between the U.S. and China in which the two nations have imposed reciprocal import tariffs on each other throughout 2018. The U.S. started the trade war in the beginning of January when it slapped a tariff on solar panel imports from China.

Oil prices are typically determined by three factors: supply, demand, and a change in the dollar’s value. Supply can be further broken down into physical and political supply-side constraint. Physical supply-side constraints are external shocks such as a war or nature disaster that physically limit a country’s capacity to produce or export oil and thus increase the price. For example, oil prices skyrocketed in the 1970s when the 1973 Arab-Israeli War and the 1979 Iranian Revolution disrupted oil exports from the Middle East.

The second component of supply, to which Trump was referring in his speech at the U.N., are political constraints to supply, which include OPEC quotas. OPEC controls roughly 44 percent of global oil production and 82 percent of proven oil reserves. Its fifteen member states coordinate action to raise or lower production quotas, affecting the global oil supply and thus, price. Starting in the 1980s, OPEC began setting production targets for member countries to keep the price of oil high. However, in recent years OPEC’s ability to influence oil prices has been challenged by internal OPEC disagreements that have made coordination more difficult.

Another factor that influences oil prices is the demand for oil and gasoline, which fluctuates seasonally. Higher levels of travel in the spring and summer months increase demand for oil and gasoline, leading to a small rise in cost during this period. Despite more demand for heating oil during the colder months, demand for oil and gasoline decreases compared to the warmer months.

Finally, the value of the U.S. dollar affects oil prices since oil transactions are conducted in U.S. dollars and many oil exporting countries peg their currency to the U.S. dollar. If the dollar’s value falls, so does the revenue which the exporting countries receive.

In brief, Trump’s claim that OPEC is manipulating world oil prices is only partly true, since OPEC quotas are just one of several factors affecting oil prices. Furthermore, they are nothing new and OPEC has been around since 1960 and has been setting quotas since the 1980s. Finally, if anything, OPEC’s sway over prices has decreased while the U.S.’s clout has increased with its increased domestic shale oil production, an upward trend which began almost two decades ago.