Extended deterrence, commonly known as the “nuclear umbrella,” represents America’s commitment to defend its allies against strategic threats, including the use of nuclear weapons. Since the late 1940s, this policy provides security guarantees to NATO members and Asian allies like Japan and South Korea.

Rising threats from adversaries like North Korea and Iran, coupled with the modernization of arsenals by Russia and China, underscore its continued necessity. Without this safeguard, allies may feel compelled to pursue independent nuclear programs, triggering preventable proliferation that can destabilize entire regions and weaken American influence.

Consider a scenario where the United States’ failure to build a peer theater nuclear capability and public statements are viewed by allies as a reduction in American nuclear commitments in East Asia. Japan, confronted by an assertive China and threatening North Korea, initiates a covert nuclear program, leveraging its advanced civilian nuclear technology and plutonium reserves. Constitutional constraints notwithstanding, mounting public anxiety could drive Tokyo toward its first nuclear test.

South Korea, facing similar security vulnerabilities, revives its previously dormant nuclear ambitions. Taiwan, under existential threat from China, sees nuclear capability as essential for survival. Alarmed by these developments, President Xi Jinping orders an accelerated attack on Taiwan and, potentially, attacks targets in South Korea and Japan to preempt support of Taiwan.

This ripple effect would yield devastating global repercussions. The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), a cornerstone of nonproliferation, ceases in relevance. Nations such as Saudi Arabia, Turkey, Germany, and Poland might explore nuclear options. With more nuclear actors in play, risks increase as a statistical probability. Diplomatic and economic instability would likely surge, potentially fracturing alliances, crippling foreign investment, and destabilizing global markets.

Extended deterrence is not merely about preventing proliferation; it provides substantial military and economic benefits as well. American allies contribute robust defense capabilities, hosting critical strategic bases essential for American operations. South Korea’s military fought alongside American forces in every conflict since Vietnam, while Japan’s formidable naval and air capabilities enhance American strategic flexibility. European NATO allies provide indispensable missile defense and air operations infrastructure, reinforcing American global power projection.

Economically, the nuclear umbrella fosters stability, encouraging foreign direct investment from treaty allies like Japan, Germany, and South Korea—three of the top investors in the US. This security framework ensures mutual prosperity and deepens economic interdependence, strengthening not just trade partnerships but long-term strategic relationships. South Korea, the world’s 14th-largest economy, thrives under this arrangement, further reinforcing cross-border trade and investment.

Upholding extended deterrence demands a long-term investment of American resources, ensuring stability across NATO. Allied nations pledged to meet defense spending commitments, emphasizing the principle that collective security thrives on shared responsibility. Given that the US allocates just under three percent of its gross domestic product (GDP) to defense, committing at least two percent is a reasonable expectation.

Eleven nations met the two percent target in 2023, up from just four in 2017. President Trump’s pressure campaign on NATO defense spending is working. If every NATO nation adhered to the two percent minimum, the alliance’s total defense budget would rise by over $100 billion annually, reinforcing military capabilities, strengthening infrastructure, and fortifying global stability.

More than just a financial obligation, honoring these agreements is fundamental to sustaining NATO’s unity and trust. Increased investment not only bolsters collective security but also eases the strain on the US, which continues to shoulder the responsibility of protecting Western civilization from instability.

Extended deterrence long served as the backbone of global stability, shaping a world where security, military cooperation, economic prosperity, and nuclear nonproliferation are upheld. Stability is not self-sustaining; it demands vigilance, action, and unwavering commitment. NATO’s legacy proves this repeatedly. From coalition forces uniting in Kosovo to prevent ethnic cleansing, to NATO-led air campaigns in Libya that dismantled an oppressive regime, alliance members stood together in moments of crisis. Joint operations in Afghanistan, where NATO countries fought side by side for nearly two decades, showcased the strength of shared commitment. Even today, as NATO fortifies defenses in Eastern Europe, the principle remains unchanged. Security is only as strong as the unity behind it.

NATO’s Article 5 is more than a pledge; it is a promise that must be upheld through action. Security is not theoretical; it is built on resources, strategy, and cooperation. The deterrence piggy bank needs deposits, not just withdrawals. If allies fail to uphold their commitments, the burden on the US becomes untenable.

The stakes could not be higher. Geopolitical tensions are rising, nuclear threats are evolving, and adversaries are watching for cracks in the foundation. The American nuclear umbrella remains a pillar of international security, but it is only as strong as the resolve behind it. Allies must step up because if they do not, the rain will come, and they will find themselves unprotected in the storm.

Brandon Toliver, PhD, serves on the A4 staff of Headquarters Air Force. The views expressed are those of the author and do not reflect the official guidance or position of the United States government, the Department of Defense, the United States Air Force, or the United States Space Force.

The Nuclear Umbrella: Reassurance or Relic in a Shifting World? was originally published on Global Security Review.

The primary objective of Biden’s integrated deterrence strategy was to harmonize and unify the efforts of various government agencies and allied nations to deter aggression from China and other hostile actors. To achieve this objective, the strategy aimed to maximise the utilisation of all available tools of American power, encompassing diplomacy, intelligence, economic assistance, and force posture decisions. Integration with allies and partners was an integral component of Biden’s deterrence strategy and would be achieved by enhancing the interoperability of allied military forces and coordinating the diplomatic and economic initiatives of friendly nations.

While the goals of integrated deterrence appear sensible, many expressed concerns about the concept. Some claimed the term was not new or unique. It simply described the implementation of any effective, tailored deterrence strategy that leverage various organisations to prevent hostile actions.

American deterrence was executed in an integrated fashion throughout the Cold War by necessity, thanks to the size and significance of the Soviet threat. Concerns were also expressed that proponents of integrated deterrence overstated the ability of sanctions, diplomacy, and other non-military tools to prevent conflict. History shows that the threat of major military action has a unique strength in deterring an enemy, especially when that threat comes from a nation with a nuclear arsenal.

Regardless of one’s stance on integrated deterrence and its implementation, a coordinated US strategy that leverages the strengths of its allies should be preferred to the alternative currently being pursued in Washington. A lack of integration in deterrence matters is evident both within the US government and in its interactions with partners and allies.

Within the United States government, there are several reported disconnects between President Trump and senior members of his administration. For example, Secretary of State Marco Rubio was first informed of Trump’s proposal to take Gaza by military force and evict Palestinians while watching a press conference held by Trump and Israeli Prime Minister Benjamin Netanyahu. Furthermore, it was recently reported that Rubio is “privately frustrated that Trump has effectively sidelined him.” More recently, Signal messages disclosed highlight significant differences between Vice President Vance and President Trump on the timing and signaling associated with strikes on Houthi targets.

This lack of vertical integration diminishes the authority that the secretary holds in meetings with both allies and adversaries. Additionally, it eliminates the potential for any exchange of ideas that could transpire within the Department of State to develop more effective policy options to present to the president.

Horizontal integration of deterrence across various departments was also weakened, partially by budgetary cuts and eliminations of entire organizations. Foreign assistance and development resources were pivotal components of the 2022 Indo-Pacific Strategy. However, extensive cuts made to the United States Agency for International Development and other government agencies by the Department of Government Efficiency did not fully consider or comprehend the regional implications or potential negative impacts on deterrence.

To date, much of Trump’s foreign policy is focused on addressing conflicts in Europe and the Middle East. A strategy for dealing with China, beyond the use of tariffs and other economic measures, is yet to be revealed. There are lessons to be learned from what has transpired with allies facing a menacing Russian threat in Europe.

President Trump consistently urges the North Atlantic Treaty Organization’s (NATO) member-states to significantly enhance their defence expenditures, even suggesting that 5 percent of their gross domestic product (GDP) may be an appropriate threshold. For those nations that fail to meet NATO’s spending guidelines, Trump stated that US military support under Article 5 may not be available. While NATO nations were increasing defense spending prior to Trump taking office (a 20 percent increase in 2024), Germany and the United Kingdom (UK) recently announced plans to further bolster defense budgets.

While additional insights into Trump’s approach to allies in the Indo-Pacific are anticipated in the coming weeks and months, Australia should draw upon several valuable early lessons. The first pertains to the long-standing Canberra tradition of analyzing and dissecting the statements and writings of senior officials within an American administration to comprehend policy. Maintaining cordial relations with officials at all levels of the US government remains prudent, but it is uncertain whether statements from senior administration officials can be relied upon to fully reflect Trump’s perspectives.

Furthermore, the current level of Australian defense spending, which accounts for 2 percent of GDP, will not meet Trump’s expectations for allies. A pre-emptive move to increase defense spending to 2.5 percent of GDP by 2027, similar to what was announced in February by the UK, would demonstrate Australia’s national commitment to addressing its deteriorating strategic circumstances and to contributing more towards its share of the alliance. If President Trump has made one thing clear to allies, it is that if they do not value their own defense neither will he.

Carl Rhodes is founder of Robust Policy and a senior fellow with the National Institute for Deterrence Studies. Carl hosts the Deterrence Down Under podcast and previously spent 25 years with RAND Corporation. Carl has a PhD in chemical engineering from Caltech.

Trump’s Disintegrated Deterrence and Lessons for Australia was originally published on Global Security Review.