Iran is following a strategy of gradually ramping up pressure on the United States as it seeks sanctions relief, rather than trying to force the issue to a resolution by triggering an acute crisis, but this should not lead to complacency about the risks of such a crisis coming about. Iran is refraining from taking any action on the nuclear front that would be cause for immediate alarm ahead of the release next week of the latest International Atomic Energy Agency (IAEA) report on its nuclear activities. This is despite having announced on Jan. 5 that it would no longer observe any of the operational limits on its nuclear enrichment program imposed by the Joint Comprehensive Plan of Action (JCPOA), without formally withdrawing from the nuclear deal and still maintaining full monitoring access and cooperation with the IAEA. Iran is likely to unveil additional measures over time, and even the current rate of low-enriched uranium (LEU) accumulation will lead to concerns about Iran's nuclear breakout time by this summer. If combined with progress on the development and production of advanced centrifuges, that could lead to the perception in the United States and Israel that Iran is approaching a decision point.
Iran has refrained thus far from making any alarming moves on its nuclear program in the wake of its announcement on Jan. 5 that it would no longer be bound by any Joint Comprehensive Plan of Action limits on its enrichment activities. However, the combination of rising stockpiles of low-enriched uranium and potential progress on the development of more efficient centrifuges could lead to a renewed debate in the United States and Israel by the summer over exactly where the "red lines" should be.
Foreshadowing next week's report, IAEA Director General Rafael Grossi recently told the Financial Times that Iran "had not done anything concrete to follow up on that (Jan. 5) announcement." They have "continued enriching at higher levels, they have continued producing more at a higher output level," but they have not done anything that would trigger a new warning from the IAEA. This implies that we will not see a uranium-235 enrichment level over 4.5 percent in the IAEA's report next week.
Iran's forbearance thus far has left France, Germany and the United Kingdom — the three European signatories to the JCPOA — still comfortable with trying to keep the agreement on life support, resisting U.S. calls for them to return the matter to the U.N. Security Council. They formally invoked the nuclear deal's dispute resolution mechanism on Jan. 14 but made it clear they would continually extend the deadline for a referral to the Security Council absent any new moves by Iran. Thus far, this has not received a firm response from the United States, which has hinted that it might seek to invoke the process itself, a move that would face stiff resistance from the JCPOA's other signatories, given that the United States withdrew from the deal in May 2018.
Iran's Advanced Centrifuge Trajectory
What could be substantive, however, in next week's IAEA report is new evidence of Iranian progress in the development and testing of more advanced enrichment centrifuges, as well as the manufacturing of additional centrifuges with throughput capacity greater than the original IR-1 model. The IR-2M, IR-4 and IR-6 models have a throughput capacity several times greater than the IR-1 and some are already in service after Iran's tranche of JCPOA violations on Nov. 5. Later models up through the IR-9 are still in development. The JCPOA prohibited such research and development work, as well as additional manufacturing. While it does not accelerate the accumulation of LEU immediately, it could lead to a sudden and drastic shortening of Iran's breakout time — the time it would need to produce enough enriched uranium for a bomb — if and when uranium hexafluoride is fed into the new machines and demonstrates their functionality. This area will be the key variable to watch for in next week's IAEA report, and indications of Iranian progress from the IAEA would be much more credible than statements from Iranian officials, who previously have often made exaggerated claims of progress on advanced centrifuges.
Iran's accumulation of LEU during the most recent reporting period ending Nov. 3 averaged 51.6 kilograms (113.8 pounds) per month, but additions to throughput capacity under the Nov. 5 violations are significant. The throughput capacity is about 50 percent above what is allowed under the JCPOA once the 164 IR-6 advanced centrifuges installed at the Natanz Pilot Fuel Enrichment Plant were joined together in a cascade, which should have happened before the end of 2019 if the work proceeded according to plan. That probably takes the accumulation rate at least up to somewhere in the neighborhood of 60 to 65 kilograms per month, if not higher, as some analysts have speculated.
Assuming that rate of growth, a stockpile of LEU of around 550 kilograms as of early November, could put Iran in possession of a "significant quantity" — enough LEU to reprocess into a single warhead, as early as this year's second quarter. To put matters in perspective, however, Iran had several times the "significant quantity" amount of LEU before the JCPOA. What is driving a shift in concerns in this iteration is the advanced centrifuges. IR-1 centrifuges have been estimated to have 0.9 separative work units of capacity per machine in a cascade, while IR-6 machines in a cascade have 6.8 units. Thus, while the breakout time is falling in any case, either a breakthrough on the newer advanced centrifuges or the availability of more IR-6s from manufacturing, which have now been proven to work, could sharply reduce breakout time.
Building Toward a Contentious Debate
The trajectory is building toward what could be a contentious debate about where the red lines should be as the U.S. presidential election approaches in November. Iran seems to want to keep pressure building on the United States in a gradual manner, driving the decision to forego enrichment to 20 percent U-235 and refrain from installing more advanced centrifuges beyond those reactivated last year, at least for now. But the potential for surprises on advanced centrifuge development and the rollout of new capacity presents a powerful wild card, one that hawkish policymakers in both the United States and Israel will argue means that the amount of LEU that should be a cause to consider preventive military action has dropped from pre-JCPOA levels.
Both U.S. President Donald Trump and the Iranian leadership would like to avoid a large-scale military clash, but incremental Iranian pressure, along with the ambiguity about how rapidly it might be able to increase its enrichment throughput capacity, will likely combine by this summer to produce renewed policy debate over the threshold for military action, even if Iran continues to refrain from installing more cascades of advanced centrifuges or enriching uranium to greater than 5 percent U-235.