The Middle East is in turmoil, more than usual. The 2015 Iran nuclear agreement with the five permanent members of the UN Security Council—the United States, U.K., France, Russia, China plus Germany—and the U.S. withdrawal from the agreement in 2018 is a central component of the turmoil.

President Trump's rationale for withdrawing from the nuclear agreement—namely, its 15-year term was too limited, and the agreement failed to address Iran's missile production or their support for terrorist groups—has, however, not received careful comment.

The history of U.S. negotiations of nuclear arms control agreements demonstrates that presidents of both parties have never before tied nuclear arms control issues to other foreign policy concerns. Nuclear weapons are so destructive, and issues of their control and treaty verification are so complicated, that every administration, until now, has isolated nuclear negotiations from other pressing foreign policy concerns in order to avoid adding negotiating difficulties to an already uniquely complex diplomacy. The priority principle has always been to separate nuclear weapons issues from other issues in order to maximize the prospects of concluding an arms control agreement.

President Kennedy, for example, did not tie eliminating, nor even curbing, Soviet support for Cuba to negotiations of the 1963 Limited Test Ban Treaty. The president's priority was to stop U.S. and Soviet nuclear weapons testing in the atmosphere, and he knew if he insisted the Soviets just modify their Cuban policy as a condition to finalizing the Treaty, then he would never get the Treaty. Similarly, President Nixon thought it imperative to limit the number of U.S. and Soviet offensive and defensive strategic nuclear weapon systems, and as such he never, for example, sought to tie the issue of Soviet control of Eastern Europe as a condition to reaching the 1972 Strategic Arms Limitations Treaty. And so President Reagan told Mr. Gorbachev to "tear down" the Berlin Wall in June 1987, but he didn't make it a condition to reaching agreement six months later on the Intermediate-Range Nuclear Forces Treaty.

Similarly, during a decade of negotiations with Iran, the United States, joined by the other five world powers, gave priority to stopping Iran from developing a nuclear bomb, recognizing that a nuclear Iran would irrevocably destabilize the Middle East. The United States and its negotiating partners knew that if, for example, they tried to get Iran to modify its support for Hezbollah in Lebanon or Assad in Syria as a condition for concluding the nuclear agreement, then they would never get the agreement.

The president's objection to the limited 15-year term can be rebutted given that all arms control agreements that the United States has entered, as well as traditional international law, provide a right of withdrawal if a party decides that "extraordinary events related to the subject matter of the agreement" jeopardize its interests. So, even an agreement of so-called "unlimited duration" can be terminated without challenge (as President George W. Bush in 2002 terminated the Anti-Ballistic Missile Treaty with the Soviet Union negotiated 30 years earlier by President Nixon).

Last year, Iran concluded that even though the other parties to the agreement opposed U.S. withdrawal, it would not get economic relief from them because the United States announced it would impose financial penalties on any country providing such relief. Iran then began to make a series of increasingly strident announcements that it was no longer bound by the agreement, culminating in response to the targeted killing of General Qassim Suleimani that all restrictions on its production of nuclear fuel are terminated—ironically reducing by 10 years the president's objection to the agreement's 15-year duration.

Whatever lessons Iran will take away from the Suleimani kill, there is little, if any, doubt that it will conclude, as has North Korea, that the United States is less likely to attack a country with nuclear weapons, and that not having a nuclear weapon is even more dangerous than having one.

David Lenefsky practices law in Manhattan. He was formerly Project Director for Arms Control at The United Nations Association-USA.