PRESIDENT OBAMA’S defense of his emerging nuclear deal with Iran as a “once in a lifetime opportunity” reminds his critics of an earlier landmark agreement, intended to end the threat of a nuclear-armed North Korea.

Prime Minister Benjamin Netanyahu of Israel and others have argued that the eventual collapse of that agreement, resulting in North Korea’s building nuclear weapons, proves that a deal with Tehran is a big mistake. Those of us who negotiated the North Korea deal know that important lessons can be learned from that experience. But they are not the ones based on the critics’ fundamental misreading of history.

Faced with the prospect of a hostile, nuclear-armed North Korea in 1994, the Clinton administration reached a deal that required the North to give up its weapons program in return for energy assistance, the lifting of sanctions and better relations with the United States. In the late 1990s, however, we caught the North Koreans cheating and, early in the George W. Bush administration, the agreement collapsed. Today, the North’s reinvigorated bomb program may be poised, as Mr. Netanyahu pointed out in his recent speech to Congress, to produce as many as 100 nuclear weapons over the next five years.

Although our policy ultimately failed, the agreement did not. Without the 1994 deal, North Korea would have built the bomb sooner, stockpiled weapons more quickly and amassed a much larger arsenal by now. Intelligence estimates in the early 1990s concluded that the North’s nuclear program was so advanced that it could produce 30 Nagasaki-size nuclear weapons a year by the end of the decade. More than 20 years later, that still hasn’t happened.