Richard Nixon normalized relations with China when it was considered a Communist menace. Ronald Reagan signed a landmark missile agreement with the Soviet Union, which had fomented unrest worldwide and persecuted Jews. The agreement eliminated an entire category of missiles. Mr. Reagan even negotiated with Iran after the Islamic Revolution, selling it arms to use in its struggle with Iraq and using the proceeds to arm Nicaragua’s contra rebels in defiance of Congress.

Image Credit... Tim Lahan

Critics complain that the nuclear deal fails to eradicate all of Iran’s nuclear program, even for peaceful energy production, and provides sanctions relief, including access to $50 billion in Iranian assets frozen in foreign banks.

But what these critics do not mention is that the basic bargain Mr. Obama agreed to — benefits in exchange for nuclear limits — was endorsed by President George W. Bush and the other major powers in 2006. Though Mr. Bush was certainly opposed to allowing Iran to build a nuclear weapon, the proposal did not demand that Iran totally dismantle its nuclear enrichment and reprocessing activities (as critics now do); it instead offered assurances that Iran would have fuel for its civilian energy program and be integrated into the international economy. Two years later, the proposal was further enhanced, but talks with Tehran never went anywhere.

Negotiating with enemies is an essential component of statecraft and can be a crucial alternative to war. Even when America was at the height of its powers, its leaders — including Republicans — knew that any successful deal would involve some compromise with the other side, not complete capitulation. Yet that is exactly what the Republicans are demanding of Iran today as they lay plans to repudiate Mr. Obama’s hard-won accord in pursuit of some mythical “better” deal.

The accord has shortcomings, as all do, and there are risks in any decision. But a preponderance of responsible opinion — the five major powers, the United Nations Security Council, most American nuclear experts and scores of leading American diplomats — have endorsed the pact as the best way to ensure that Iran does not get a nuclear weapon.