That maxim, sometimes attributed to President Franklin Roosevelt, has frequently served as a credo for U.S. foreign policy. During the Cold War, the United States made common cause with too many dictators to count. A partial list includes: Fulgencio Batista, Anastasio Somoza, Ferdinand Marcos, Mobutu Sese Seko, Augusto Pinochet, Mohammad Reza Pahlavi (the former shah of Iran), Mohammed Zia ul-Haq, Syngman Rhee and Suharto.

But the United States has also been the greatest force for freedom over the past century. It has assisted in the overthrow of tyrannies not only in hostile states — the fascist dictatorships in Japan, Italy, and Germany; the Communist dictatorships in Russia and Eastern Europe — but also, occasionally, in allied states such as the Philippines, Egypt, Panama, South Korea and Taiwan. So when does an “S.O.B.” cross the line and engage in conduct that makes it impossible for the United States to support him any longer?

That question is prompted by two recent deaths — one in Istanbul, the other in Kandahar, Afghanistan. The gruesome torture and murder in Istanbul of Washington Post contributing columnist Jamal Khashoggi has cast an unwelcome spotlight on the Trump administration’s man in Riyadh, Crown Prince Mohammed bin Salman, who is suspected of ordering this foul deed. The murder in Kandahar of the police chief, Lt. Gen. Abdul Raziq, along with the provincial governor and intelligence chief, shines an equally unsparing spotlight on how the United States has outsourced the war in Afghanistan to brutal and corrupt warlords. Both men were — and, in the crown prince’s case, still are — valued U.S. allies, but their methods are not for the faint-hearted.

As recounted by Dexter Filkins for the New Yorker, Mohammed, who is commonly known as MBS, has a forceful way of settling disputes. When a land-registry official hesitated to help him seize a parcel of property, “MBS sent a single bullet in an envelope to help change his mind. On the Saudi streets, MBS became known as Abu Rasasa, or ‘father of the bullet.’ “

MBS has also ordered a military intervention in Yemen that has killed at least 16,000 civilians, kidnapped the prime minister of Lebanon, blockaded Qatar, and held 500 of the richest men in the Saudi kingdom hostage to extract billions of dollars in ransom. Many of the detainees were physically abused.

Raziq was a much smaller-scale malefactor than MBS but, within his own sphere, he could be even more savage. The Atlantic had a valuable primer on him in 2011: Reporter Matthieu Aikins interviewed two boys who were tortured by Raziq’s men because they were wrongly suspected of smuggling food to the Taliban; and he presented convincing evidence that Raziq had massacred 16 men in a tribal dispute and then claimed they were Taliban fighters killed in battle. And this is only a small sample of his crimes.

Yet both the Obama and Trump administrations pretended not to notice Raziq’s human-rights abuses or his links to the drug trade, because his heavy-handed methods kept Kandahar calm. “If you need a mad dog on a leash, he’s not a bad one to have,” one U.S. official said in 2010.

I have always had doubts about this realpolitik policy. In 2010, I was part of a team of civilians advising Gen. David Petraeus, then the commander in Kabul. We concluded that the No. 1 force driving Taliban recruitment was the abuses and corruption of the Afghan regime. Raziq was Exhibit A: Even by Afghan standards, he was a vicious S.O.B. But the United States continued backing him until his death, which occurred Thursday shortly after he met with Lt. Gen. Austin “Scott” Miller, the current U.S. commander in Afghanistan.

That is an unsavory but understandable choice because, for all his sins, Raziq was preferable to the Taliban, and it was not clear that anyone else could maintain even a modicum of stability in the south. Whoever does replace Raziq, he is likely to be just as unscrupulous, because the Afghan state is so weak that it remains dependent on warlords.

It is a different story in Saudi Arabia. It has a much stronger state that is much less dependent on one man — even when that man is the crown prince. If MBS were found complicit in Khashoggi’s murder and forced to step down, that would not spell the end of the monarchy or the U.S.-Saudi alliance. MBS took over as defense minister and deputy crown prince only in 2015, and as crown prince in 2017. Saudi Arabia existed for 83 years without MBS in high office, and there is no shorter of older and more experienced princes who would be delighted to oust him — just as he ousted them.

While MBS did enact some long overdue liberal reforms — allowing women to drive, for example — he also acted far more recklessly both inside and outside the kingdom than had been the norm for previous Saudi rulers, who ruled in more restrained and consensual fashion. If he ordered the death and dismemberment of a U.S. resident who wrote for an American newspaper, MBS finally went too far. This is a crime that has seized public attention around the world, and one that not even President Donald Trump can ignore, much as he would plainly like to.

We can afford to hold MBS accountable. He is one S.O.B. we don’t have to live with.