Visitors to a future Donald J. Trump presidential library may find a whole section dedicated to his demolition of the 2015 Iran nuclear accord: “worst deal ever”; “horrible” and “one-sided”; “major embarrassment”; “defective at its core.”

As Mr. Trump pursues North Korea’s denuclearization at the Singapore summit meeting scheduled for Tuesday, he risks being hoisted on his own hyperbole. By Mr. Trump’s own logic, any deal with the North has to be better, tougher, more comprehensive than the Iran accord. Even if the North’s leader, Kim Jong-un, is operating in good faith — a historically big if — that outcome is highly unlikely. Paradoxically, the best deal Mr. Trump can reach with North Korea more than likely will look like what Barack Obama achieved with Iran.

The Iran deal required Tehran — up front — to eliminate 98 percent of its uranium stockpile, dismantle and put under seal two-thirds of its centrifuges, cap uranium enrichment at levels well below weapons-grade and remove the core of its plutonium reactor. The effect was to push Iran’s “breakout capacity” — the time it would take the regime to produce enough material for a single weapon — from weeks to over one year. A sweeping inspections regime would ensure Iran was making good on its commitments.

Mr. Trump argued the deal was “disastrous” because some of the limitations on Iran’s enrichment and reprocessing capacity expire over 10 to 25 years — even though the prohibition on Iran acquiring a nuclear weapon and the inspections regime are permanent — and because the accord did not directly address Iran’s missile program, its malicious activities throughout the Middle East or its human rights abuses at home.