Mr. Trump’s critics are asking us to believe that the priority for stabilizing the Middle East today is distancing the United States from one of its oldest allies and instead working to achieve a balance of power between Riyadh and Tehran. The Saudis, they claim, need us far more than we need them.

This is a dangerous assumption that is not born out by experience. In recent years all of America’s allies, from Mr. Sisi in Egypt to Recep Tayyip Erdogan in Turkey to Benjamin Netanyahu in Israel, have begun spending as much time in Moscow as in Washington. Why would we think the Saudis might not also seek protection from Russia if they are shunned by America?

Instead of standing with the Saudis, Mr. Trump’s critics call for, as Senator Lindsey Graham recently did, sanctions that would persuade King Salman to appoint a new crown prince. But King Salman is not the de facto ruler of Saudi Arabia; Prince Mohammed is. A policy that seeks to change the king’s mind is based on a delusion that is far more deranged than anything in Mr. Trump’s statement.