Income inequality and greedy billionaires are neither seen nor heard from in Senator Bernie Sanders’s sober-minded new foreign policy ad, “Defend This Nation.”

On Screen

Mr. Sanders, identified in a caption, addresses the camera in a suit jacket (but no tie): “As president, I will defend this nation, but I will do it responsibly,” he promises. A white flashback drives home his point, showing George W. Bush, Dick Cheney and Donald H. Rumsfeld in a meeting of Mr. Bush’s wartime cabinet. Mr. Sanders says he voted against the Iraq war, “and that was the right vote.”

As moody documentary-style music and the sound of a camera shutter keep a brisk pace, photographs flicker by showing that war and its toll: bombed-out buildings, an infant being carried through a battlefield by a weeping mother, shouting Middle Eastern protesters, American soldiers in war-torn streets, and finally a triple-amputee Army sergeant who was wounded in Afghanistan, hunched over in rehabilitation. “We must never forget the lessons of that experience,” Mr. Sanders says.

“ISIS must be destroyed,” he continues, back in the frame, but “we should not do it alone.” An animated map shows black arrows slowly invading and constricting the Islamic State’s splotchy orange territory, as Mr. Sanders calls for an “international coalition with Muslim boots on the ground, fighting with our support.” He concludes: “It’s time to end the quagmire of perpetual warfare in the Middle East. As president, I will.”