As former military leaders, we see removing the threat of an Iran armed with nuclear weapons to be an imperative. 

But seriously ill-timed would be any demand that “all instruments of power and influence of the United States should remain on the table to prevent [Iran] from developing nuclear weapon capabilities.”  Negotiations often entail posturing and saber rattling, and sometimes even overt threats.  But for sake of our troops, overt threats before concluding what appears to be earnest, ongoing negotiations is unwise.  Wholly apart from the aggressive tone, America’s adversaries know that the U.S. never goes to war without “all instruments of [our nation’s] power on the table.”  For the soldiers who will bear those arms, we would expect no less. 

To be clear:  We do not believe that the international community should allow Iran to continue its program, and simply hope for the best.  But hope is neither a strategy for avoiding war, nor a viable alternative to it.  Sound negotiations offer the only viable alternative to war.

Our 238-year history as a nation includes instances of clear threat that left no viable alternative to war.  The dispute here is over the nature and purposes of Iran’s nuclear research program. 

The phrases “good faith negotiation,” and “force as a last resort”, at a minimum, require genuine, strategically-focused efforts that truly exhaust every diplomatic alternative to war. Our troops in uniform, their families, and those innocents inevitably caught in the crossfire deserve the very best that our diplomats can do to effect a constructive, non-kinetic resolution to this dispute.

A successful negotiation can serve as a major step towards eliminating the threat of nuclear weapons and the technology to produce them. It will assure Iran’s neighbors and Israel that their respective security needs are protected – without forcing us to take sides in regional ethnic and religious disputes.  And it will respect the dignity of all nations, Iran included.

These three goals each are important, and will each require compromise. And each, we believe, can be achieved without resort to war.

After thirty-five years without diplomatic, business, or cultural relations, our nation’s leaders are pursuing the only viable alternative to war.  We urge each member of the House and Senate to lend strong support for a negotiated solution and to permit the ongoing negotiations to proceed in an environment conducive to success.  No decision a soldier makes is more basic than when to squeeze a trigger.  The Iranian leadership is more than acutely aware that we are fully capable of pulling the trigger on more sanctions, when and as we consider it necessary.  The question here is one of timing.

The Constitution provides a distinct role for Congress in the making of foreign policy. The Senate is empowered to advise the president during treaty negotiations, and to consent or reject proposed treaties. Congress as a whole is empowered to lift or maintain existing sanctions, and to impose new ones.  Until the negotiations are over, it is vitally important that we stand united in support of administration’s efforts to negotiate an agreement acceptable to Iran, its neighbors, and Israel.

The alternative is war, and the costs of destroying Iran’s capacity to weaponize nuclear power, while an absolute imperative if necessary, and well within our means, those costs will be substantial. 

Even with courage and hard work, the U.S. and P5+1 negotiating an effective agreement with Iran that is sufficiently verifiable may not be possible.  We must remain committed to erase any remnant of threat, but how and when we do that with force really should be determined only after diligent efforts at diplomacy fail. 

Until they fail, however, we prefer Theodore Roosevelt’s approach: Let us “speak softly.” Everyone knows we have the big stick.  Let us make sure we don’t swing it prematurely.

Clark was NATO's Supreme Allied Commander Europe from 1997 to 2000 and commanded Operation Allied Forces in the Kosovo War. He is an active Democrat and ran for the Democratic presidential nomination in 2004. Reeder is a former U.S. Army undersecretary.