Washington is reimagining its global role, leading the U.S. Department of Defense (DoD) to make difficult choices about priorities, resources, and risk to better address the long-term “pacing challenge” posed by China. To do so, the United States plans to accept risks in the Middle East and against future Iran threats. Iran’s possession and potential use of weapons of mass destruction (WMDs)—specifically, its nuclear program, chemical weapons, and biological agents—pose the greatest threat to U.S. interests and Washington’s ability to accept risk in the region. But how Iran might leverage WMDs to threaten U.S. interests and upend Washington’s plans to make trade-offs in global responsibilities is unclear, while the risks of failing to address these challenges remain high. As a result, the DoD and its component organizations, such as the Defense Threat Reduction Agency (DTRA), must enhance their understanding of the threat posed by Iran’s nuclear, chemical, and biological capabilities and the escalation dynamics surrounding Iranian WMDs during crisis and conflict. By doing so, the United States can better accept risk in the Middle East and revise its global priorities while still protecting core U.S. interests.

To improve the DoD’s understanding of future Iranian WMD-related threats and escalation dynamics, the Gaming Lab at the Center for a New American Security (CNAS) conducted a series of three virtual strategic-operational tabletop exercises (TTXs) exploring future Iranian nuclear, chemical, and biological weapons use. The TTXs indicated that even if Iran acquires a nuclear weapon, the likelihood the regime will use it is low. Instead, the regime may be more likely to use chemical and biological weapons to escalate conflict. Moreover, there are significant asymmetries between American and Iranian views of conflict timelines, escalation redlines, and risk tolerance, all of which make it difficult to offer and signal credible ways to de-escalate a crisis. Differences between Washington’s risk acceptance and that of its regional partners—Israel, in particular—further complicate U.S.-Iran interactions.

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Read the full report at the Center for a New American Security.