The economic sanctions have worked. Iran has paid a steep price for its clandestine pursuit of the capability to produce nuclear weapons, for its dodging international monitoring and other restrictions. There is logic then in thinking that continued, or even stronger, sanctions ultimately will bring a deal in which Iran takes such steps as dismantling centrifuges, shipping its nuclear fuel out of the country and opening its doors to intrusive inspections.

Yet Iran has come knocking now, in the form of Hassan Rouhani, its new president with a narrow window to improve the economy and engage the international community. In that way, President Obama rightly pointed to having a “profound responsibility” to test whether there is a diplomatic path to Iran giving up its nuclear program. The president made the argument on Saturday as negotiators reached an interim deal, each side conceding something as part of setting the stage for talks about a long-term accord.

The worry has been that Iran would take advantage, any temporary agreement amounting to little more than cover for pressing ahead. That remains a possibility. Yet Iran has conceded significant ground, freezing its nuclear program for six months, by, among other things, curbing its uranium enrichment and halting the installation of centrifuges. In exchange for this holding action, the United States and its partners will provide modest relief from economic sanctions.

After three decades of poisoned relations between Washington and Tehran, any level of trust will develop slowly. So, the deal struck in Geneva reflects what is realistic. What it does not represent is a giveaway of some kind, or a “historic mistake,” as Benjamin Netanyahu, the Israeli prime minister, put it. The door is open. If Iran rejects the opportunity, the economic and diplomatic screws can be tightened.

Hard to believe the international community wouldn’t respond vigorously to Iranian defiance.

So there is a strong fallback position. And if the next round of talks proves productive? The way will be there to achieve the more secure world the president described, Iran without nuclear weapons, no longer the international pariah, its posture enhancing the security of Israel and Saudi Arabia, plus other Arab states.

That’s not to say such a turn will come easily. This interim agreement leaves many difficult questions to resolve, requiring tough and uncomfortable choices for both sides.

Thus, it is imperative to push hard in testing Iranian intentions. Worth stressing, too, is that effective negotiations require give and take, parties with an eye on what will build relationships. Consider that Iran has made much of its wish to continue enriching uranium. Netanyahu argues that allowing any such capability would be reckless. Yet the risk can be managed with adequate restrictions, monitoring and inspections. Such are the makings of an enduring agreement, one that got closer over the weekend.