Impact of the US Exiting Its Alliances? Potential Rise in Nuclear-Armed Nations, Global Conflict, and Excessive Costs for Large-Scale Combat

By Matt Lensing, MTI Contributor

Scholars point to the United States’ role in global treaties and alliances as investments to prevent large-scale conflicts, and nuclear warfare. However, this has only truly been the case since World War II. The United States has previously adopted periods of isolationist policy to avoid foreign entanglements. With an incoming Presidential administration that appears less inclined to keep the status quo with foreign relationships it is worth considering the implications for the U.S. if they were to leave defense agreements, like the North Atlantic Treaty Organization (NATO).

Recent publications consistently raise three major concerns without U.S. participation in global alliances:

  1. Increased Nuclear Proliferation – Without U.S. protection to treaty partners more countries will try to get their own nuclear capabilities thus increasing the rise in quantity of nuclear weapons and people with access to them. 
  2. Increased Global Conflict – Allies dissuade partners from unilateral military action against other countries, and organizations, to support regional and global stability. Without formal ties the U.S. potentially loses bargaining power to de-escalate conflicts.
  3. Excessive Economic Costs to Deploy Troops and Material – If pulled into another global conflict the short-term cost of military expenditures would far exceed the annual cost of supporting current military partnerships.
Increased Nuclear Proliferation

During the Cold War U.S alliances and treaties aimed to curb communist expansion, but a key motivation for keeping them has been to limit the number of nuclear armed countries. The U.S. does this by providing assurances of their vast nuclear umbrella to smaller nations.

South Korea and Japan do not have nuclear weapons despite their neighbor, North Korea, being a nuclear power. It is extremely likely South Korea and Japan would seek their own nuclear arsenal to defend themselves if the U.S. no longer guaranteed their defense. As Hal Brands and Pete Feaver put it, “security guarantees and forward deployments have played a critical role in convincing historically insecure and technologically advanced countries – Germany, Japan, Taiwan, South Korea, amongst others – to forgo possession of the world’s absolute weapon,” (Brands & Feaver, 2017). South Korea and Japan have the knowledge and capability to build nuclear weapons but have refrained, which is similar in Europe.

Britain and France are the only other NATO countries aside from the U.S. with nuclear weapons. However, they only have, “500 warheads between them, compared with America’s 5,000 and Russia’s nearly 6,000,” (Can Europe defend itself without America?, 2024).However, the nuclear shortcomings for the rest of NATO are more than quantity as Britain, “depends on America for the design of future warheads and draws from a common pool of missiles, which is kept on the other side of the Atlantic,” (Can Europe defend itself without America?, 2024). Thus, British nuclear capabilities rely on the U.S. for rearmament and development. 

Without nuclear commitments from the United States European nuclear deterrence weakens especially in the face of the significant imbalance between the rest of NATO and Russia. Thus far alliances, and pledges of military support, have prevented nuclear conflict, but they have also limited conventional wars.

Increased Risk of Conflict

Critics of alliances feel the potential of U.S. entrapment in foreign wars might result from obligations of support to allies. Most cited is Article 5 of the NATO Treaty, which says an attack against one member is considered an attack against all. The U.S. could defend allies with military force, but ambiguous language in treaty agreements provides them flexibility in their responses using loopholes, sidestepping, diversification, and dual deterrence, (Beckley, 2015). 

Loopholes – allies may choose to interpret the term ‘aggression,’ differently, and even if a country’s leader believes support of a treaty ally is necessary their own government still holds veto power. 

Sidestepping – providing the smallest amount of support to an ally without risking their own critical military assets. 

Diversification – mitigating the risk of entanglement by having an ample collection of alliances. Since the U.S. is ally to so many countries, they are aware that support to one will potentially infringe on another agreement, so they are more apt to seek non-military solutions to disputes.

Dual Deterrence – simultaneously deterring aggressors and restraining allies; convincing one country not to strike another if both parties agree to de-escalate tensions.

Military alliances offer a wider range of options to respond to aggressors. In the Indo-Pacific region without alliances the U.S. would have limited, “options short of actual resort to force… to shape North Korea calculations: either taking relatively meaningless actions, such as changing the alert levels in the homeland or other theaters, or taking relatively dramatic escalations, such as moving an aircraft carrier battle group within range of the Korea peninsula or flying sorties close to the North Korean border,” (Brands & Feaver, 2017). Instead, the U.S. can boost the military readiness of North Korea’s neighbors to achieve deterrence effects while simultaneously increasing their own missile defense capabilities. 

A recent example to deter the People’s Republic of China (PRC) was the U.S. decision to leave a Typhoon missile system in the Philippines after recent exercises, which supports the existing U.S.-Philippines Mutual Defense Treaty, (Gomez, 2024). 

Excessive Costs to Deploy Equipment and Personnel to Global Conflicts

Another criticism of alliances is free-riding partners taking advantage of the U.S. With a more defensive strategy the U.S. could reduce defense spending to, “2.5 percent of Gross Domestic Product (GDP) compared to 3.5 or 4 percent,” (Brands & Feaver, 2017). In contrast the U.S. could lose revenue from the foreign economies that they are military partners with as bilateral trade increases based on the number of U.S. troops deployed to a given country, (Brands & Feaver, 2017). However, the largest impact will be costs to move military equipment and personnel around the globe.

In both World Wars the U.S. was late to enter the conflicts. Before an Allied invasion of mainland Europe was possible the U.S. economy had to completely shift to meet mobilization demands, which took three years after formally declaring war against Japan. Learning from its mistakes the U.S. decreased costs for future conflicts by setting up relationships with allies for basing and support.

An example of this are the overseas U.S. garrisons in Germany and Japan occupied since the end of World War II, and in South Korea since the Korean War. Interestingly, “host-nation support arrangements often make it roughly as cheap, if not cheaper, to station American forces overseas than to station them in the United States,” (Brands & Feaver, 2017). The pre-positioned equipment and access to ports also significantly reduces the transit time to move forces into a theater of operations. During Operation Desert Shield, leading up to Desert Storm, the U.S. Army sent Germany based units to the Middle East first because of their closer proximity.

Allies help the U.S. cut costs in case of large-scale combat. In addition to easing the burden of deploying everything from the United States they also provide compatible systems and weapons, so the U.S. does not have to bring everything to a fight. Leaving alliances will force the U.S. to redevelop their strategy from working as a part of a coalition to going it alone.

Conclusion

Historically Americans view participation in international alliances and treaties differently based on the threat of global conflict. Having a network of military allies to train and exchange technology with is favorable when the risk of war is low. However, as the number of potential conflict flashpoints increase Americans tend to view alliances with skepticism. Despite the perceived risk of taking part in multilateral treaties countries are still eager to signup.

Both Finland and Sweden became NATO members in 2023 and 2024 respectively and are increasing their military expenditure to match participation requirements. Sweden specifically is experiencing strain from military spending initiatives and personnel shortages to meet the required levels expected of NATO members, (Khorrami, 2024). Prior to 2022 Sweden spent an average of 1.85% of GDP on military expenditures but now will spend over 2.2% based on their new defense spending bill. For smaller countries, especially those with a perceived immediate threat, joining alliances appears a worthwhile investment despite the burden of defense spending. 

However, for the U.S. the benefit of alliances is less tangible. America carries more than its share of the financial, material, and personnel burden in the alliances it anchors, but the alternative may be a situation where, “crises more frequently take on a nuclear dimension and the risk of nuclear conflict is higher,” (Brands & Feaver, 2017). As well as a world where the U.S. will have to go it alone for any military response, at the cost of appearing hegemonic, and will have to re-establish the infrastructure set up over the last 80 years to surge personnel, equipment, and manufacturing to respond to global conflicts.

Matt Lensing is an active duty infantry officer who has served in the U.S. Army since 2007.

Works Cited:

  • Beckley, M. (2015). The Myth of Entangling Alliances: Reassessing the Security Risks of U.S. 
  • Defense Pacts. International Security, 39(4), 7-48.
  • Brands, H., & Feaver, P. D. (2017). What Are America’s Alliances Good For? The US Army War College Quarterly: Parameters, 47(2), 15-30.
  • Can Europe defend itself without America? (2024, February 18). The Economist. Retrieved August 5, 2024, from https://www.economist.com/briefing/2024/02/18/can-europe-defend-iself-without-america
  • Gomez, J. (2024, September 25). US missile system will remain in Philippines despite China’s alarm. Retrieved from DefenseNews: https://www.defensenews.com/global/asia-pacific/2024/09/25/us-missile-system-will-remain-in-philippines-despite-chinas-alarm/
  • Khorrami, N. (2024, October 23). Sweden’s Defense Overhaul: Prioritizing NATO, Baltic Security, and Space Capabilities. Retrieved October 24 , 2024, from https://www.wilsoncenter.org/article/swedens-defense-overhaul-prioritizing-nato-baltic-security-and-space-capabilities

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