President Donald Trump doesn’t understand his chief responsibility as president. It is not to make deals and create jobs. It is to protect the security and liberty of Americans. By that standard, the Kingdom of Saudi Arabia is not a “truly spectacular ally,” as he claimed.

Saudi Crown Prince Mohammed bin Salman, the KSA’s de facto ruler, is a brutal, even sadistic, murderer. Worse for Washington is the affront to the U.S.

America protects the corrupt, licentious, and oppressive Saudi royal family. Yet Riyadh did not hesitate to ostentatiously murder Jamal Khashoggi, who had taken refuge in the U.S.

Rated unfree by Freedom House, the Kingdom allows not even a hint of political or religious liberty. There is not one church, synagogue, or temple in the KSA. Iran is a beacon of religious toleration in comparison.

Moreover, MbS has tightened political controls even as he has relaxed social strictures. Personally a big spender on yachts and chalets, he launched a supposed crusade against corruption, which turned out to be a revenue-raising expedition targeting potential critics among Saudi Arabia’s elite.

Historically the KSA has been a dangerous breeding ground for terrorists, funding fundamentalist Wahhabism around the globe and providing 15 of 19 9/11 hijackers. Saudi money enriched al-Qaeda and other radical groups; the regime backed jihadists in Syria and through its invasion of Yemen freed up radical groups, including al-Qaeda in the Arabian Peninsula.

Riyadh’s brutal aggression against Yemen created a humanitarian catastrophe and empowered Iran. Kidnapping Lebanon’s prime minister benefited Hezbollah. Attempting to isolate, and then threatening to attack, Qatar pushed the latter toward both Tehran and Ankara.

In Syria Riyadh backed radical forces which came to dominate the opposition. As for Iran, U.S. interests would be best served by a balance of power, not hegemony as sought by MbS.

Rarely has an assassination been carried out so incompetently yet ostentatiously. Even President Trump was forced to admit that the journalist was murdered, by a massive hit squad, in a brutal manner, by the Saudi government, in its diplomatic facilities.

Nevertheless, the president decided it does not matter if MbS was involved in Khashoggi’s murder. Apparently based on the belief that KSA is a “truly spectacular ally,” by which President Trump means it buys U.S. weapons and other products.

Yet America’s chief executive is a pitiful negotiator. The KSA needs America far more than America needs the KSA.

The Saudis’ supposed $110 billion weapons buy has yielded little more than a tenth as much cash. In any case, the purpose of alliances should be to enhance U.S. security, not boost arms sales.

Still, Riyadh is going to continue purchasing American weapons for its own reasons. It could diversify suppliers, but for logistical reasons the Kingdom has reason to continue its relationship with the Pentagon.

If nothing else the royal regime needs spare parts and training to maintain its forces. That need will only grow if Riyadh no longer can count on America to protect it from its own folly.

Commercial sales beyond weapons are even less important to America’s $20 trillion economy. If MbS is serious about reforming his nation’s energy-dependent economy, he is going to deal with American companies. Anyway, a presidential desire that the Saudis buy products as well as lobbyists and think tanks is not a good reason to insulate a murderous, irresponsible, and reckless regime.

The administration should stop acting like it is beholden to MbS. The U.S. should end all support for the Yemen war. Weapons sales should be placed on hold.

This doesn’t mean the administration need treat Saudi Arabia as an enemy and refuse to deal with MbS. After all, American presidents engaged Joseph Stalin, Mao Zedong, and Kim Jong-un.

In dealing with ugly, brutal, and authoritarian regimes the president’s transactional approach makes some foreign policy sense. However, there should be no exaggerated expressions of fervent friendship, no illusions about shared values, and no attempt to sugarcoat Riyadh’s sustained assault on human rights and American interests.

In particular, the U.S. should indicate that while Washington recognizes the Saudis will choose their own leadership, the U.S. will be forced to look to its own interests. That means confronting MbS’ irresponsible actions and aggressive reach for hegemony, which are destabilizing the region.

The KSA is not an ally in any real sense. Working together when appropriate should never be confused with endorsing or even accepting such a malodorous regime.

Doug Bandow is a Senior Fellow at the Cato Institute. A former Special Assistant to President Ronald Reagan, he is author of Foreign Follies: America’s New Global Empire.