Saudi Arabia is dismayed by President Obama’s Middle East policy. Its leaders feel that he does not play by the rules that have governed the Saudi-American alliance for decades: The United States provides security guarantees in return for the Persian Gulf states’ reliable stewardship of their oil reserves and support for American regional dominance.

In the Saudis’ view, Mr. Obama has betrayed their interests, often in favor of their enemy, Iran. Having concluded that the United States is no longer a reliable ally, they’ve decided they must go it alone as a regional power, while also strengthening the country’s domestic economy. In both instances, though, the kingdom is overplaying its hand. The Saudis can’t, in reality, stand up to Iran, nor can their domestic reform agenda deliver, especially if the country remains embroiled in regional conflicts. Failure on both fronts could drag the United States back into the region militarily.

A token of Saudi resentment was on display last week when Mr. Obama was received by the governor of Riyadh rather than by the king — a rare snub for a sitting American president. As the visit concluded, American officials asserted that the meeting had “cleared the air,” but the signs of a rift that predates the Obama presidency were fully apparent.

The relationship has been rocky since the Sept. 11, 2001, attacks, when it became clear that 15 of the plane hijackers were Saudi citizens. Mr. Obama’s visit coincided with controversy over a bill before Congress that would enable victims of the attacks to sue the Saudi government — a vivid reminder of the long-running tensions. (The Saudis have threatened economic reprisals if the bill passes, even though the White House has said the president would veto it.)

Yet there is truth to the Saudis’ sense that the Obama administration has attenuated the alliance. The Saudis were shocked when America withdrew its forces from Iraq in 2010 and left Nuri Kamal al-Maliki, a pro-Iranian Shiite, in charge as prime minister. This abandoned Iraq’s Sunnis to the sectarian Mr. Maliki’s mercy, which indirectly abetted the rise of the Islamic State in Iraq.

The final straw came with the American-led nuclear deal with Iran in 2015. While this froze Iran’s nuclear program in return for lifting economic sanctions, it placed no constraints on Iran’s ability to project power, either directly or through proxies, across the region, from Lebanon and Syria to Iraq and Yemen.

The Iran deal came soon after a new king assumed power. King Salman and his son Mohammed, who is deputy crown prince and minister of defense, are the most hawkish and ambitious rulers in modern Saudi history. As Mr. Obama uses American power more selectively, the Saudis have stepped in militarily, backing jihadist groups against the government of Bashar al-Assad in Syria and mounting an air war against the Houthi rebels in Yemen. Not satisfied with only taking on Iran’s proxies, the Saudis severed diplomatic relations with Tehran in January after they executed an outspoken Saudi Shiite cleric.

Saudis and non-Saudis alike used to complain about the paralysis of Saudi policy making. Not any more. Now the complaints are of sudden, erratic shifts. The result has been more instability in an already turbulent region. Saudi Arabia will not be able to militarily dominate Iran: It has neither the manpower and the expertise nor the broad network of proxy forces that the Iranians have.

The kingdom has also thrown caution to the wind in the domestic arena. The House of Saud knows it must diversify its economy, moving away from oil and providing new sources of employment for its young population. The plan to sell off a share of the highly prized national asset, the state-owned oil and gas company Saudi Aramco, as well as privatizing parts of the health and education sectors, shows how far Riyadh is prepared to go.

Yet the Saudi economy — still deeply dependent on state spending — is unlikely to generate the $100 billion of annual non-oil government revenue envisaged for 2020. Outside the oil sector, its technocratic resources are limited and its capacity for private enterprise is stunted. Many seasoned technocrats believe that playing with the governance of Saudi Aramco, by far the kingdom’s best-functioning institution, is risky.

The kingdom’s understandable desire to increase its geopolitical standing and economic autonomy risks overreaching. America can help mitigate this situation. Saudi Arabia needs the American alliance for economic as well as security reasons. It needs to increase foreign investment to finance both the reform program and its ballooning deficit. A clear signal that the United States, the Saudis’ biggest investor, will continue security cooperation would ease foreign investors’ jitters, as well as calm the Saudi leadership.

Despite the surface tensions, King Salman and Prince Mohammed are by temperament and conviction deeply pro-American. It would be a desperately wasted opportunity for Washington not to take advantage of this.

As unpalatable as cooperation with the kingdom might be for some, cutting it adrift is worse. Whatever the resentments, neither side has a realistic alternative to the other — something President Obama has clearly had difficulty reconciling himself to.

This article was originally published by The New York Times.