Counterproliferation in U.S. Policy

Counterproliferation in U.S. Policy

Counterproliferation in U.S. Policy

August 18, 2025 (IN12597)

The United States uses diplomatic, military, law enforcement, intelligence, and financial means to disrupt, preempt, or respond to the acquisition or use of nuclear, biological, or chemical weapons, also referred to as weapons of mass destruction (WMD). This effort has sometimes included threatening or using military force. Since the 1990s, the U.S. Department of Defense (DOD) has referred to this policy as counterproliferation. The Clinton Administration's 1993 Counterproliferation Initiative responded to the changing security environment at the end of the Cold War and largely sought to prevent additional states or non-state actors from acquiring WMD. Following the September 11, 2001, terrorist attacks, the George W. Bush Administration expanded this strategy to include "preemptive" use of force against WMD threats.

Counterproliferation may involve a variety of policy tools, including intelligence collection and detection of proliferation activity, intelligence operations, cyber operations, special operations forces activities, and interdiction of WMD-related shipments. Related nonproliferation policies are meant to prevent the spread of nuclear, biological, or chemical weapons to new states or non-state actors through treaties, international organizations, sanctions, and export control arrangements. Congress oversees the development, funding, execution, and direction of DOD and other federal agency counterproliferation-related programs. In part through hearings and legislation, Congress is evaluating and responding to the June 2025 U.S. military strike against Iran's nuclear program, which Trump Administration officials say was intended to "destroy or severely degrade Iran's nuclear program."

What Is Counterproliferation?

National security strategy documents have outlined U.S. counterproliferation policy goals. The most recent DOD Strategy for Countering Weapons of Mass Destruction, published in 2023, includes a plan to "degrade actor capability to develop, acquire, or use WMD." The strategy outlines requirements for DOD to "possess the capabilities to directly degrade adversary pathways to developing WMD" and directs the department to develop activities with allies and partners to "disable or defeat WMD threats prior to use in conflict." Regarding use of military force, the strategy states, "The Department will act in coordination with partners whenever possible, but will act unilaterally if necessary to degrade others' WMD and related capabilities. Where possible, the Joint Force [i.e., the collective U.S. armed services] will be prepared to counter WMD employment through missile defense, missile defeat, and specialized agent defeat capabilities." In DOD, Special Operations Command (USSOCOM) has coordinating authorities for the counter weapons of mass destruction (C-WMD) mission.

Counterproliferation and nonproliferation activities are part of dedicated programs at DOD; the Departments of State, Energy, the Treasury, Commerce and Justice; and the intelligence community. The U.S.-led Proliferation Security Initiative coordinates with international partners to disrupt the acquisition of WMD-related material through interdiction of shipments. The National Counterproliferation and Biological Security Center under the Director of National Intelligence (DNI) was formed in 2005 (as the National Counter Proliferation Center) to provide interagency coordination to identify and address WMD threats. The Department of Homeland Security Countering WMD Office supports federal, state, and local authorities through deployment of bioterrorism, nuclear, and radiation detection technology, as well as emergency preparedness training.

Selected U.S. Use of Force in Counterproliferation

The United States may decide to counter WMD with the threat or use of military force when U.S. officials assess that other means, such as diplomacy or sanctions, have not been successful. This may occur when officials assess that WMD development has progressed to a level that might threaten the United States or its allies. Some observers have argued for preemptive or preventive strikes against WMD programs as a counterproliferation tool, but others have questioned whether such actions undermine international law or evade Congress's role in authorizing use of force. The below list, which contains instances in which the United States used military force against nuclear, biological, or chemical weapons-related facilities, is drawn from CRS Report R42738, Instances of Use of United States Armed Forces Abroad, 1798-2023:

August 1998. U.S. strike, Operation Infinite Reach, on the Al-Shifa Pharmaceutical Factory in Khartoum, Sudan, an alleged chemical weapons (CW) production site with possible connections to Al-Qaeda.

December 1998. U.S. and UK bombing campaign, Operation Desert Fox, against Iraqi industrial facilities deemed capable of producing WMD, and against other Iraqi military and security targets.

March 2003. U.S. and allied military campaign, Operation Iraqi Freedom, authorized by Congress (P.L. 107-243) and UN Security Council resolutions citing Iraqi WMD programs.

August-September 2013. U.S. threat of military force against Syria for CW use. President Barack Obama requested congressional authorization for the use of military force against Syria in response to CW attacks on civilians by the Syrian regime; before a vote was taken, Syria agreed to a diplomatic agreement on CW disarmament.

April 2017. U.S. air strikes on April 6 against the Syrian Al Shayrat airfield, where CW used in an April 4, 2017, attack allegedly was based.

April 2018. U.S. operation with France and the UK to destroy the Syrian CW research, development, and production capabilities.

June 2025 U.S. Strikes on Iranian Facilities

U.S. Operation Midnight Hammer struck three Iranian nuclear facilities on the night of June 21, 2025. According to U.S. officials, the strikes' objective was "to severely degrade Iran's nuclear weapons infrastructure." President Donald Trump's letter to Congress described the June airstrikes' purpose: "[t]he strike was taken to advance vital United States national interests, and in collective self-defense of our ally, Israel, by eliminating Iran's nuclear program." The attacks' net impact on Iran's nuclear program is unclear. Members of Congress could continue to assess the costs and benefits of the operation. Congress also may weigh the attack's implications for Iran or other countries' decisions to pursue or foreswear nuclear weapons, its possible impact on allies and partners, and its influence on adversary military and foreign policy calculations. Members of Congress also may continue to debate the legal authorities underpinning such an action, under U.S. and international law. Congress also could consider whether and to what extent the operation fits into the Administration's overall national security strategy.