The basics in this game of chicken are well known: President Barack Obama doesn’t want to attack Iran. But he doesn’t want Israel to attack Iran, either. So in advance of his Monday meeting with Israeli Prime Minister Benjamin Netanyahu, Obama knew he had to do something unusual to dramatize his willingness to take military action, down the road, if other measures fail to stop Iran from obtaining a nuclear weapon.

Obama chose the interesting tactic of deliberately narrowing his options, at least the public formulation of them, in an interview published Friday with Jeffrey Goldberg of the Atlantic magazine. It was Obama at his most emphatic and articulate, and it was a clever way to communicate over Netanyahu’s head with an Israeli public that suspects his sincerity and toughness.

The Obama comments that interested me most were the ones in which he sought to make commitments about future U.S. action—and to explain why they were sound policy choices for the United States, not just for Israel. That’s a crucial part of his messaging to Iran and the world: To show that he isn’t being jammed by Israel into these promises, but is making them because they’re rational and sensible for the United States.

The crucial line in the interview was this: “We are going to continue to apply pressure until Iran changes course.” That implies a steady process of escalating economic sanctions, increased sabotage and other covert action, additional pressure on allies and neighbors—and if all that doesn’t work, then, yes, a U.S. military strike on Iranian nuclear facilities that would inflict far more damage than the Israelis could.

When Goldberg asked if Obama would take the same position if Israel weren’t in the picture, he anchored the policy in pragmatic U.S. national interests, as opposed to charitable actions on behalf of a politically potent ally: “This is something in the national-security interest of the United States and the world community,” Obama said, adding later: “I’m not saying this is something we’d like to solve. I’m saying this is something we have to solve.”

By grounding the commitment in “realism” and U.S. national interest, I thought Obama made it far more credible. “There is no good reason to doubt me on these issues,” he said—a dubious claim before the interview with Goldberg, somewhat less dubious after.

The other point that struck me was Obama’s clarity about establishing a “red line” between an Iranian civilian nuclear program (acceptable) and a weapons program (unacceptable). A key issue here is whether the U.S. would have sufficient strategic warning to detect an Iranian breakout from the former to the latter. Obama answered yes: “Iran does not yet have a nuclear weapon and is not yet in a position to obtain a nuclear weapons without us having a pretty long lead time in which we will know that they are making that attempt,” he said.

His message to Israel: If the Iranians cross this red line, the United States will attack. He explained at another point that his approach “pushes much further to the right whatever potential breakout capacity they may have.”

Is Obama bluffing? Who can say, but if you’re an Iranian decision maker (or, perhaps more important, Netanyahu) you have to weigh a bit more heavily the possibility that the president really does mean what he says.