The report said the 2010, 2018 and 2022 Nuclear Posture Reviews argued for strengthening extended deterrence and described it as supporting U.S. nuclear nonproliferation goals. It also noted that the 2026 National Defense Strategy did not explicitly mention extended deterrence, instead saying allies and partners would “take primary responsibility” for their own defense with “critical but more limited U.S. support.”
Some members of Congress have raised concerns about the Trump administration’s commitment to extended deterrence and about possible interest among some allies in acquiring their own nuclear weapons. The report referred to that possibility as so-called “friendly proliferation.”
Since the start of the Cold War, the United States has threatened to use military force, including the possible first use of nuclear weapons, in response to Soviet armed aggression against Western Europe. U.S. policymakers viewed that risk of escalation as a credible deterrent against a potential Soviet attack.
The United States later provided assurances to several allies in Asia that their security would be backed by U.S. nuclear weapons. The report said U.S. policy has sought to extend the American “nuclear umbrella” over allies in Europe and Asia partly to reduce incentives for them to develop nuclear weapons.
The report said doubts about the credibility of U.S. extended deterrence could lead allied governments to seek additional security assurances or improve their security through other means. Those options could include independent or cooperative nuclear capabilities, or the pursuit of “nuclear latency,” meaning the technical ability to develop nuclear weapons.
During the Cold War, the United States deployed various nonstrategic nuclear weapons in allied countries. After the Cold War, it reduced nuclear forces, including those stationed abroad, and narrowed the scenarios in which it would consider nuclear use, while not adopting a “no first use” policy.
The United States currently extends nuclear deterrence through forward-deployed nuclear weapons, U.S.-based aircraft that could be deployed in a crisis, and strategic nuclear forces. The stated purpose of regional nuclear deterrence capabilities has been to deter limited nuclear use and nuclear coercion by Russia, China and North Korea.
Regional capabilities include dual-capable aircraft operated by the United States and some NATO allies under NATO’s nuclear burden-sharing arrangements. These aircraft can carry the B61 gravity bomb, which is deployed from some NATO bases under U.S. operational control.
The U.S. Navy also deploys the W76-2 low-yield warhead on the Trident II D5 submarine-launched ballistic missile. In 2024, the Navy also began a programme to procure a nuclear-armed sea-launched cruise missile.
In 2026 testimony, U.S. Strategic Command Commander Navy Adm. Richard Correll said the United States was seeking to “accelerate the development and deployment of additional theater nuclear capabilities.” The report said Congress may oversee how such capabilities fit into broader regional security architectures.
In the Euro-Atlantic region, NATO says “nuclear weapons are a core component of [the Alliance’s] overall capabilities for deterrence and defense, alongside conventional and missile defense forces.” NATO describes U.S., British and French strategic nuclear forces as the “supreme guarantee” of security for its 32 member states.
NATO has moved to strengthen deterrence since Russia’s 2022 invasion of Ukraine. The report noted that the United Kingdom and France pledged in the July 2025 Northwood Declaration to “deepen their nuclear cooperation and coordination,” while French President Emmanuel Macron announced a new “forward deterrence” strategy in March 2026.
In the Indo-Pacific, Japan, South Korea and Australia have expressed concern about changes in Chinese and North Korean nuclear weapons and other military capabilities. The United States maintains conventional forces in Japan and South Korea but no longer forward-deploys nuclear weapons in the region.
The United States has mutual defense arrangements with Japan and South Korea and conducts extended deterrence consultations with both countries. After the 2023 Washington Declaration, Washington and Seoul created a Nuclear Consultative Group.
Officials in Japan and South Korea have publicly discussed nuclear weapons issues, according to the report. Both governments continue to say they do not seek their own nuclear weapons and support stronger extended deterrence, including through trilateral cooperation.
The report also noted the U.S.-Australia alliance under the 1951 ANZUS pact, while pointing out that U.S. defense commitments to New Zealand were suspended in the 1980s after changes to New Zealand’s nuclear weapons policies. It said the United States and Australia continue to conduct a Strategic Policy Dialogue.
Congress plays a central role by authorizing and appropriating funds and overseeing programmes relevant to extended deterrence. Members may also engage directly with allied leaders and review intelligence on the military capabilities of Russia, China, North Korea, Iran and other states.
The 2023 report of the Congressional Commission on the Strategic Posture of the United States argued that “any major change” to U.S. strategic policy or posture should be “predicated on meaningful consultations” with allies. The CRS report said Congress may continue to review U.S. engagement with allies and efforts to assure them of the credibility of American defense commitments.
The report said some allies in Europe and the Indo-Pacific may request changes to existing extended nuclear deterrence commitments. It also said allies and partners in the Middle East and elsewhere may seek protection under a U.S. “nuclear umbrella.”
Congress may continue to debate investments in regional nuclear and nonnuclear capabilities, including programmes such as the nuclear-armed sea-launched cruise missile. The report said those debates are likely to focus on whether U.S. capabilities are sufficient to deter regional adversaries and reassure allies.
