Barack Obama and Hillary Clinton were asked in a recent presidential debate whether they would meet with such controversial foreign leaders as Venezuelan President Hugo Chávez and Cuba's Fidel Castro.

Despite the sparring between the two over the timing and pre-conditions for such a meeting, they both essentially said they would engage international reprobates – something this administration has repeatedly balked at doing. Remember, Vice President Dick Cheney said, "We don't negotiate with evil. We destroy it."

A tougher question is whether the next president would threaten to use nuclear weapons against a foreign enemy. Four Republican candidates – Mitt Romney, Duncan Hunter, Jim Gilmore, and Rudy Giuliani – have already expressed their willingness to use "tactical" nuclear weapons against Iran to prevent it from obtaining nuclear weapons. Again, this tracks with the vice president who is reportedly urging an attack on Iran's nuclear infrastructure by next year at the latest.

Mr. Obama recently told the Associated Press that he would not use nuclear weapons "in any circumstance" involving civilians. Mrs. Clinton once again criticized his foreign policy position saying that she didn't believe that "any president should make any blanket statements."

If the Democrat candidates want to distinguish themselves from their opponents, and if the Republicans want to recover from the disastrous foreign policy of this administration, the candidates should commit to delegitimizing – not stressing – nuclear weapons. Every time the United States threatens a potential adversary with nuclear weapons it tells the world that these weapons are acceptable instruments of modern warfare and that there are no political or moral constraints on US behavior.

It is overwhelmingly in the US national interest to preserve the "taboo" on nuclear weapons use and to seek to reduce the salience of nuclear weapons in US security policy. To achieve this, the candidates should address four issues:

First, announce that they reject nuclear intimidation and the current policy of preventive war. In the future, and under their leadership, the United States will retain its nuclear arsenal for deterrence only and will not employ nuclear weapons except in retaliation for a nuclear attack.

Second, commit to the eventual elimination of all nuclear weapons. Even President Reagan sought a nuclear-free world and a number of senior US statesmen, from the late Paul Nitze (Democrat) to George Schultz and Henry Kissinger (both Republicans), agree that the US would be much safer in a world without nuclear weapons.

Third, declare that they plan to withdraw all US nuclear weapons from Europe during their term in office. These weapons are relics of the cold war: There is no strategic requirement for them, and no military mission that cannot be carried out by conventional weapons.

Finally, make it clear that the United States will not resume nuclear testing. A reaffirmation of the decade-old moratorium on nuclear tests (or ratification by the next Congress of the treaty banning such tests) would strengthen US efforts to control the spread of nuclear weapons to other nations.

In the run-up to the presidential election, the candidates of both parties have a chance to indicate to the world that the next administration will forgo the policy of nuclear intimidation and actively strive to delegitimize nuclear weapons. This nation cannot become more secure by reserving for itself the right to use nuclear weapons while preaching nuclear abstinence for the rest of world.

• Jack Mendelsohn was a US State Department official, a member of the US SALT and START delegations and deputy director of the Arms Control Association. He is presently an adjunct professor at George Washington University and American University.