This is in part because Mr. Paul’s views align naturally with Mr. Trump’s much more than with Mr. Graham’s. Both the president and Mr. Paul favor engagement, including with North Korea and Russia.

The fact remains that while Mr. Graham’s friendship and Trump-whispering may well be the only thing standing between America’s high-tailing it out of Kabul and staying put, it isn’t indicative of a fundamental alignment — or a fundamental realignment — of foreign-policy views between the commander in chief and a guy from the John Bolton wing of the party.

Lucky for Mr. Paul. For years, the Republican Party wasn’t buying what he was selling. But now, thanks to Mr. Trump, their friendship and Mr. Trump’s natural instincts combined with his malleability, it’s no longer Mr. Paul versus the entire party where Syria — or anywhere else — is concerned. Mr. Trump has mainstreamed Paulite thinking on America’s international relations, whether you like it or not.

Mr. Paul’s cultivated friendship with the president has paid dividends in other policy areas. Small-ball though it may seem, executive action on association health plans was something Mr. Paul sought, and got, from the president. And out of self-interest in the Russia investigation or not, Mr. Trump has also helped to mainstream within the Republican Party traditionally Paulite — and very much not Bushite or Cheneyish — concerns about government surveillance of its citizens (or in this case the Trump campaign).

Will all this mean the end of “endless wars”? In fact, Mr. Trump doesn’t seem quite as keen on getting out of Western Asia and the Arabian Peninsula wholesale as Mr. Paul would like.

On this, the president has actually united Mr. Paul and Mr. Graham in opposition. Take his decision last summer to sell billions of dollars of munitions to Saudi Arabia. Both senators opposed that action and were part of bipartisan legislation intended to block the arms sale.

“The reason I’m voting with Senator Paul and others today is to send a signal to Saudi Arabia that if you act the way you’re acting, there is no space for a strategic relationship,” Mr. Graham said, referring to Jamal Khashoggi, the Saudi journalist killed in 2018. “There is no amount of oil you can produce that will get me and others to give you a pass on chopping somebody up in a consulate.”