As the next round of negotiations over Iran’s nuclear capabilities opens this week, the P5+1group has staked out its official line. According to their negotiators, the interim deal with Iran has halted aspects of Iran’s nuclear activities and even led to some rollback of the program.

This position sounds nice, but it isn’t the whole story: Unfortunately, it leaves out some crucial facts. Missing from this narrative is that in some important respects, Iran’s nuclear program is also progressing dangerously.

The most important issue that constitutes, rather than a retreat, a “roll-forward” of the program regards research and development on ever more advanced generations of Iranian centrifuges. Over the course of December 2013-January 2014, Iran and the P5+1 argued over the extent of R&D that Iran was allowed under the interim agreement, but the P5+1 was ultimately forced to concede that the language of the Joint Plan of Action (their interim agreement) did not prevent Iran from conducting R&D into any aspect of advanced new generation centrifuges, as long as it does not operate them. This includes the IR-8 model, which Iran has announced it intends to begin testing.

This is not a small matter. When stockpiles of low enriched uranium – which Iran continues to churn out (and actually at an increased rate, because the centrifuges that were producing 20 percent enriched uranium have now been recommissioned to enrich to the 5 percent level) – are fed into the advanced centrifuges under  development, spinning many times faster than the ones currently in use, Iran will very quickly be able to enrich to the high levels needed for nuclear weapons.

This is not the outcome that the P5+1 wanted, but due to the ambiguous language inserted in the interim deal – in order to try to smooth over basic differences  between the two sides – the international negotiators exposed themselves to Iranian manipulation.

Indeed, Iran’s nuclear program thrives on ambiguity. Iran tries to avoid action that can easily be construed as an outright violation of an agreement, and gets where it wants to go by exploiting ambiguity – beginning with the ambiguous formulations of the NPT itself.

Ambiguity provides a cover for Iran’s interpretations and actions, and must be avoided at all costs in any new deal with Iran.

Iran will also be working hard in the coming months of negotiations – as it did regarding negotiations on the interim deal – to avoid including issues that will seriously undermine its ability to maintain a military nuclear option. Iran insists it will not close down facilities at Fordow and Arak, nor dismantle even one centrifuge. Two additional topics that Iran will resist including in the context of a comprehensive deal are its ballistic missile capabilities and what is known as the Possible (better called ‘Probable’) Military Dimensions of its nuclear program. The P5+1 cannot agree to leave any of these issues unaddressed in a final comprehensive deal with Iran.

The issue of ballistic missiles was raised in recent weeks, as Iran carried out new tests, and the U.S. stated its intent to address the issue in any comprehensive deal. Ballistic missiles are a crucial component of a nuclear weapons capability, but Iran is strongly resisting their inclusion in the talks on the grounds that they are not in and of themselves “nuclear.

But ballistic missiles are already included in UN Security Council resolutions on Iran, and it would be ludicrous to leave them out of a comprehensive deal.

Clarifying the Possible Military Dimensions of Iran’s nuclear program is also of central importance to any comprehensive deal. Iran has stonewalled investigation into the PMD for years; it continues to refuse the IAEA entry into Parchin or to clarify the full list of concerns that the IAEA has about its nuclear activities of a purely military nature, including experiments with neutron initiators and research into nuclear warhead design. The last time the IAEA published its concerns was in a special annex to a report back in November 2011.

A disturbing piece published by Reuters in late February this year reports that the IAEA was poised in 2013 to compile a major report on Iran, with more evidence of its weapons-related research, but that the idea was dropped in light of the election of Rohani and renewed negotiations with the P5+1.

It is truly misguided to desist from delving into past military-related activities in order not to “upset” the Iranians or interfere with negotiations on a new deal. Any comprehensive deal must reveal the military dimensions of Iran’s program. First, in order to expose Iran as having lied and cheated for decades, which means it can no longer hide behind the mantra that it has “done no wrong” and therefore has no obligation to make a deal. Second, because verification of Iran’s future activities critically depends on understanding how the country was deceiving the international community in the past. As such, clearing up past Iranian activities is critical to current assessments, and to any future deal reached with Iran, that hinges, as U.S. negotiator Wendy Sherman has said, on verification. Therefore, we cannot “leave the past in the past”.

The U.S. must take the lead in ensuring that the critical elements noted here are included in any comprehensive deal with Iran. Two weeks ago, Senator Robert Menendez provided sharp and to-the-point analysis of the situation at the AIPAC conference in Washington DC. Hopefully the Obama administration in the coming months will be on the same page on these important issues, and display the necessary determination to confront Iran and its ongoing intransigence and blatant lack of good faith on the nuclear front.

Dr. Emily B. Landau is a Senior Research Associate at the Institute for National Security Studies (INSS). She is the author of Decade of Diplomacy: Negotiations with Iran and North Korea and the Future of Nuclear Nonproliferation (2012). Follow her on Twitter: @EmilyBLandau