The U.S. and Iran will engage in the first substantive diplomatic conversation in more than three decades as a result of overtures made by the new Iranian head of state, which to most observers came somewhere out of the blue. Why they were made, and where they will lead, is all conjecture, but they nevertheless are a point of demarcation in which a new narrative may begin on relations between the two countries.

And significantly, not just between the two countries, but possibly in the larger context of the disposition of Western interests in all of the volatile Middle East.

Nothing would be more gratifying than a shift away from the 34-year saga of suspicion and animosity that has marked U.S.-Iranian relations, frequently leading to the precipice of all-out military conflict.

The potential significance of the meetings at the United Nations headquarters between Iran's Foreign Minister and the U.S. Secretary of State cannot be understated. It is the first time since 1979 in which words between the two countries are likely to amount to something beyond thinly veiled threats.

At the top of the agenda should be the status of Iran's nuclear program, just as diplomatic talks scheduled at the U.N. with Syrian leaders will address that country's stockpile of chemical weapons. Should both discussions proceed and amount to something beyond theater, it would be ground shifting.

Already, the willingness expressed by Syria's Bashar Hafez al-Assad and Iran's new head of state, President Hassan Rouhani, to engage in diplomatic counsel over important matters is a dizzying development that has altered the dynamic of the U.S. posture toward the two countries. "For the United States," President Barack Obama said in his address to the U.N., "these new circumstances have also meant a shifting away from a perpetual war-footing."

Even a temporary respite from a readiness for war is a good thing. For it to be more than temporary will depend on the sincerity of the overtures made by Assad and Rouhani, and whether both leaders are indeed willing to act as responsible members of the international community.

For both, it's a tough sell, given the history of blustering and subterfuge practiced by both the Syrian leader and the predecessors of Iran's new president. The United States has an obligation to require thorough and believable verification of any agreement to disarm, and it cannot back off its demands that both nations end their programs to build or obtains weapons of mass destruction.

But their stated willingness to engage in diplomacy has opened a rare doorway to a possible path toward more stability in the region. Because such opportunities have been infinitesimally scarce in recent decades, it is in the best interests of the United States to engage cautiously in talks with both nations, until there is good reason to no longer do so.