Iran threatens 90% enrichment: How close is Tehran to a nuclear weapon? | DW News

Key Concepts

• Uranium Enrichment: The process of increasing the percentage of the isotope U-235 in uranium to make it suitable for nuclear fuel (low enrichment) or weapons (high enrichment, typically 90%).
• Cascades: A series of centrifuges connected together to progressively enrich uranium gas.
• 60% to 90% Threshold: The technical "breakout" phase where uranium, once enriched to 60%, can be rapidly processed to weapons-grade (90%) levels.
• Pit: The core of a nuclear warhead made of weapons-grade metal.
• IAEA (International Atomic Energy Agency): The UN agency responsible for monitoring nuclear programs and ensuring compliance with non-proliferation treaties.
• JCPOA (Joint Comprehensive Plan of Action): The 2015 Iran nuclear deal designed to limit Iran's enrichment capabilities in exchange for sanctions relief.

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1. The Current Threat and Strategic Context

Iran has threatened to increase its uranium enrichment levels to 90%—the threshold for weapons-grade material—if the current conflict with the U.S. escalates. While Iran claims its nuclear program is for peaceful purposes, experts argue this is no longer credible.

• The "Leverage" Argument: Former NATO official William Alberi suggests Iran’s enrichment activities were a calculated move to gain negotiating leverage. By moving closer to the threshold, Iran reduced the time required to build a bomb from years to months, and eventually weeks.
• Credibility Gap: Alberi notes that no country with a purely civilian nuclear program requires 60% enrichment. The IAEA has reached a point where it can no longer certify that Iran is not pursuing military capabilities.

2. Technical Process: From 60% to a Warhead

Alberi outlines the complex, multi-stage process required to transition from current stockpiles to a functional nuclear weapon:

1. Centrifuge Processing: Iran currently holds approximately 440.9 kg of 60% enriched uranium in gaseous form. This must be fed through centrifuges to reach 90% purity.
2. Chemical Conversion: The 90% enriched gas must be converted into a solid form, then into a metal form.
3. Weaponization: The metal must be fashioned into a "pit" (the sphere at the center of a bomb) and integrated into a warhead assembly.

• Expert Assessment: While the transition from 60% to 90% is rapid, the subsequent stages of metal conversion and warhead assembly are "incredibly complex" and require specialized facilities. Under wartime conditions and international monitoring, these steps are highly risky and would likely trigger a direct military intervention by the U.S. or Israel.

3. Status of Nuclear Infrastructure

The effectiveness of previous U.S. and Israeli strikes on Iranian facilities is a subject of debate:

• Declared vs. Undeclared Sites: While "declared" facilities monitored by the IAEA (such as above-ground sites) have been largely destroyed or severely disrupted, Iran has invested heavily in subterranean tunnel complexes.
• Hidden Facilities: There is significant concern regarding undisclosed, mountain-based tunnel complexes (such as those near Natanz) that may be used to house hidden centrifuge cascades.
• Esfahan: This facility is identified as a critical site for fuel fabrication and potential metal conversion, making it a primary target for disruption.

4. Strategic Priorities for Containment

Alberi identifies a clear hierarchy of urgency regarding the Iranian nuclear program:

• Immediate Priority: Securing and eliminating the existing stockpile of 440.9 kg of 60% enriched uranium and hundreds of kilograms of 20% enriched uranium. The goal is to remove this material from the country or "down-blend" it to prevent its use in a weapon.
• Secondary Priority: Destroying the centrifuge infrastructure. While the centrifuges are essential for future enrichment, they are a "future concern" compared to the immediate threat posed by the already-enriched material.

5. Synthesis and Conclusion

The situation regarding Iran’s nuclear program is characterized by a high-stakes game of brinkmanship. While Iran’s declared nuclear infrastructure has been significantly degraded by recent strikes, the existence of hidden, underground facilities creates a persistent intelligence gap. The consensus among experts is that Iran has moved beyond the scope of a peaceful program, using high-level enrichment as a strategic tool. The most critical objective for international actors is the physical removal or neutralization of the existing enriched uranium stockpile, as the technical hurdles to weaponization—while significant—are no longer insurmountable if Iran decides to cross the final threshold.