Every three months, approximately, the International Atomic Energy Agency releases a report on Iran’s nuclear program. The media summarizes the technical details — the latest levels of enrichment, kilograms of enriched uranium hexafluoride, numbers of installed centrifuges — but misses the true meaning of these figures. Those numbers, if analyzed, convey how much time Iran would need to produce enough highly enriched uranium for a nuclear weapon, and how much that “breakout window” could shrink in the near future. That information is critical — but currently not easily available — to policymakers or the public, even as they debate what to do about Iran’s continuing nuclear progress.

Three administrations, from both parties, have declared it unacceptable for Iran to obtain nuclear weapons. President Barack Obama has made abundantly clear that his policy is to “prevent, not contain” a nuclear Iran. He and members of this administration have repeatedly pledged to use “all elements of American power” in pursuit of that objective. But an effective policy cannot be designed without reference to time.

In choosing tools to pressure Iran’s leadership to give up its military nuclear ambitions, an important consideration must be how long those measures will require to take effect; will it be before, or after, Iran has developed a nuclear weapons capability? No matter how effective, policies that take too long to yield results cannot meet the goal of preventing a nuclear Iran.

Appropriate policies for preventing a nuclear Iran cannot be developed without two pieces of information: how much time it would take to detect and respond to an attempt to produce fissile material, thereby “breaking out” of the safeguards and limitations imposed on it by IAEA regulations; and how soon Iran will be able to produce enough fissile material for a nuclear device faster than it would take to detect and respond to such a break out. If Iran’s break out window grows too small, it will enter the zone of undetectability — where it will be almost impossible to react to and stop an Iranian attempt to produce weapons-grade uranium — rendering a policy of prevention moot.

Intelligence agencies, think tanks and experts analyze available data to estimate this information. Our work at the Bipartisan Policy Center, for example, suggests that right now, it would take Iran about 100 days, a little over three months, to produce 20 kilograms of 90 percent enriched uranium, enough for a nuclear weapon. That window, according to our analysis, could slip below six weeks — our estimate of the threshold of undetectability, or the minimum time it would take to detect, mobilize and respond to an Iranian break out — in mid-2014.

But the results of such studies are not part of the public debate about Iran policy. They ought to be. The Bush administration was criticized for its lack of transparency leading up to the invasion of Iraq and for politicizing intelligence. To avoid similar charges, the Obama administration should present the American public with credible evidence about the status of Iran’s nuclear progress and engage in a robust debate about what ought to be done about it, and when. To enable such reasoned discussion the Bipartisan Policy Center’s Iran Task Force — led by former Sen. Charles Robb and retired Gen. Charles Wald, along with former members of Congress, military leaders, and diplomats from both parties — recommended creating an independent, government-appointed study group that would regularly report on how close Iran is to a nuclear weapons capability.

The House of Representatives is voting on, and the Senate is discussing, a similar provision that is perhaps one of the most important, yet overlooked, elements of bipartisan legislation: the Nuclear Iran Prevention Act of 2013, championed by Foreign Affairs Committee Chairman Ed Royce, R-Calif., and ranking member Eliot L. Engel, D-N.Y. In addition to important measures that further tighten sanctions against Iran, this legislation directs the president to report to Congress every 60 days on Iran’s progress toward break-out capability. Such reporting would allow the public to intelligently consider the urgency of the Iranian threat and what to do about it.

In the end, public debate might be the most important tool for convincing Iran to accept a negotiated settlement to their nuclear standoff. If, when presented with the evidence, the American public supports the administration’s determination to use every means necessary to prevent a nuclear Iran, Tehran might be persuaded that America does not bluff, that Iran’s evasion, defiance, and recalcitrance will not pay off. But for that debate to occur, the public requires more than just the raw technical data provided by the IAEA. It’s about time we had a credible assessment of Iran’s nuclear timeline.

Blaise Misztal is the acting director of the Bipartisan Policy Center’s Foreign Policy Project.