Trump and and the American Unilateralism

1. The Trump Doctrine and American Unilateralism

Almost every president has a guiding policy “doctrine”, whether it be the Truman Doctrine of anti-communist containment, Carter Doctrine on control of the Persian Gulf, or the Monroe Doctrine on foreign intervention in the Western Hemisphere. Since the 47th President’s entry into the White House, the “Trump Doctrine” has stood as the guiding principle of U.S. foreign policy. In theory, it follows that America’s needs are of primary concern, and multilateral aid, support, and institutions with heavy reliance on U.S. funding and engagement, should be reduced, minimized, or eradicated.

It was introduced in Trump’s first term in office and acts as a departure from the nation’s tacit historic role of being a global peace-maker and ‘good cop’ of the global power order. This shift has taken form many ways, with one example being the dismantling of U.S. institutions used to promote civil society as well as democracy globally, including but not limited to the Agency for International Development, Voice of America, and the National Endowment for Democracy (Haass, 2025).

This move from traditional U.S. support for multilateral institutions has prompted many to reconsider the historical role of these institutions and their future relevance. Since World War I and World War II, the United States has played a significant role in international policing, often in a unilateral manner, whether through Cold War containment efforts in Vietnam during the 1960s, interventions like Grenada in 1983, Korea in 1950, or the orchestration of Saddam Hussein’s removal during the 2003 Iraq invasion.

While unilateral action has long been a feature of U.S. foreign policy, often employed when strategic interests were at stake, such actions were typically framed within broader commitments to global leadership or moral responsibility. In contrast, Trump’s approach is different in that unilateralism and isolationism are not occasional strategies, but guiding principles of his foreign policy. Unlike past interventions such as Korea or Iraq, which asserted America’s leadership even while bypassing multilateral approval, Trump’s stance has framed international institution engagement as a liability rather than a responsibility. The Monroe Doctrine, with its emphasis on hemispheric dominance and limited foreign entanglement, continues to exist in American thinking, but Trump’s interpretation leans further toward transactional disengagement and reduced global responsibility.

This prompts thought on what lies in the future for U.S. foreign policy. The extent to which multilateral institutions can recover from the aftermath of Trump’s second four year term (potentially eight) remains unclear. Much will depend on the direction of future administrations. A Democrat victory may aim to rebuild these partnerships, whereas another Trump-aligned figure could cement the current trajectory of retreat. One of the clearest regions where these changes have played out is in the Middle East, a region long shaped by American interventionism.

For decades, U.S. foreign policy in the region has served as a test for wider global strategy, whether it be Cold War containment, oil-driven alliances, or counterterrorism campaigns. From the 1953 coup in Iran to the 2003 Iraq invasion, successive presidents have used both hard and soft power to secure U.S. interests, often under the banner of promoting stability or democracy. While each administration has employed different tools, they shared an underlying belief in sustained engagement, albeit frequently unilateral, rooted in the assumption that American leadership was essential to shaping the region's future, and framed as to their benefit.

The Trump administration, by contrast, recalibrated this relationship. Moving from relying on long-term diplomatic structures and peacebuilding efforts, the emphasis in his first term shifted toward transactional diplomacy. This was most evident in the recognition of Jerusalem as Israel’s capital and the withdrawal from the Iran nuclear deal, actions that reflected a disregard for international consensus and consideration for multilateral diplomacy (The White House, 2018; Landler, 2017). These actions reshaped America's credibility in the eyes of many, as European allies were unsure whether U.S. commitments to the region would remain intact beyond a single term.

Under Trump, military disengagement is also portrayed as a strength. The sudden drawdown of troops in Syria, weakened trust among Kurdish allies, while bolstering the influence of Russia and Iran. The U.S. as of 2025 now has less than 1,000 troops in the country (The Japan Times, 2025). Instead of upholding the U.S.'s traditional role as regional stabiliser, the Trump Doctrine prioritises short-term gain over long-term partnerships, often with the assumption that others would step into the vacuum, which has proven to be true.

Meanwhile, institutions that had once bolstered U.S. soft power, USAID, Voice of America, and the National Endowment for Democracy, have been either sidelined or completely shut down, furthering the ideological pivot away from global aid and support (Kenny, 2025).

Whether the Biden administration’s partial return to multilateralism and alliance-building repaired any of the damage from Trump’s first term is unclear, but also irrelevant due to Trump’s second term. The precedent set by Trump in his first term and the precedent he is setting now, suggests that neo-isolationism is a growing force in American political Republican identity, if not essential to its core. The U.S.'s future role in the Middle East, and indeed in the international order, now hinges not just on elections, but on whether the American public believes in the value of global leadership, and the need for an American global presence, which future elections will reveal.

2. The UN and Declining U.S. Commitment to Multilateral Peacekeeping

During Donald Trump's first presidency, the United States demonstrated a notable decline in commitment to the United Nations and its peacekeeping operations that he has maintained going into his non-consecutive second term. This was primarily through funding cuts and hostile rhetoric. In 2018, the Trump administration reduced U.S. contributions to UN peacekeeping by around $600 million, arguing that the burden of global security should be more equitably shared among member states (Carver, 2018). Trump consistently framed international institutions like the UN as inefficient and overly reliant on U.S. support, aligning with his “America First” ethos. This narrative framed the UN as an organisation that was exploiting American generosity. The administration also withdrew from several UN bodies, including the Human Rights Council and UNESCO, citing perceived anti-American or anti-Israel biases, a sentiment that also led to his sanctions on the ICC in 2025 (The White House, 2025).

The reduction in U.S. funding and political support under the Trump administration has had tangible effects on several UN peacekeeping missions. As the largest single contributor to the UN’s peacekeeping budget in 2017-18, providing approximately 28.5% before Trump’s cuts, the U.S. 2018 withdrawal created financial shortfalls that forced missions to scale back operations (Beaumont, 2017). In conflict zones such as the Democratic Republic of Congo (MONUSCO) and South Sudan (UNMISS), missions faced operational constraints, including reduced personnel, limited mobility, and the downsizing of protective and humanitarian functions.

Some have claimed, missions like MONUSCO have actively brought destabilisation, allowing perpetrators of the Rwandan genocide to take over refugee camps (Rubin, 2025). It also could be that the withdrawal of symbolic U.S. backing has weakened the political legitimacy and authority of these missions, allowing host governments and armed groups to challenge UN presence. In the Democratic Republic of Congo, President Félix Tshisekedi’s government formally requested MONUSCO’s withdrawal by the end of 2024, citing the mission’s inability to restore stability, an assertion that reflected both mounting domestic dissatisfaction and diminished international support (Nantulya, 2024).

For traditional allies, particularly in Europe and within NATO, doubt has been cast on America’s reliability as a global leader and security partner. European powers like Germany and France have been prompted to explore more autonomous defense strategies, including renewed investment in EU-led missions and serious discussions around a potential European army. An example is the expansion of the EU’s Permanent Structured Cooperation (PESCO) and proposals for a European rapid-reaction force, directly led by concerns over U.S. unpredictability (Boot, 2025). However, German Chancellor Merz has openly declared that, even amid discussions of strategic autonomy, Berlin “still needs the United States” to guarantee its defense, showing that the talk of European independence may be incompatible with current political realities (Chassany, 2025).

For adversaries, this retreat created openings for geopolitical gains. Russia and China, in particular, capitalised on the vacuum left by the U.S., increasing their influence in peacekeeping operations and diplomatic bodies. China, ramped up its financial and personnel contributions to UN peacekeeping and put forward stronger leadership in global governance discussions (Lee & Himani, 2025). The erosion of U.S. engagement signaled a possible shift in the international order, encouraging alternative powers to contest Western liberal norms with greater confidence.

3. NATO and the Strain on Transatlantic Security

Trump has been consistently critical of NATO, particularly concerning what he perceives as unfair burden-sharing among member states. He argued that the United States was disproportionately funding the alliance while other countries, especially in Europe, were failing to meet their financial commitments. Trump frequently cited the NATO guideline that each member should spend at least 2% of their GDP on defense, something fewer than a third of members were doing during his first term (CNN, 2018).

At the 2018 NATO summit in Brussels, Trump publicly chastised allies like Germany for relying heavily on U.S. military protection while investing relatively little in their own defense capabilities (Mason & Emmot, 2018). He even threatened them with his “go it alone” policy if allies didn’t increase their spending, (a trade doctrine he still uses today, most recently seen at the Paris OECD summit) casting doubt on the U.S.’s commitment to Article 5, NATO’s collective defense clause (Foster, 2025).

Trump’s aggressive stance on NATO burden-sharing, mixed with current global affairs, has significantly affected the alliance's idea of collective defense. While the Trump administration’s ideological retreat from multilateralism led to a measurable increase in defense spending among several NATO member states, particularly in Eastern Europe, this also introduced issues in alliance unity. Poland, for example, raised its defense spending from 2.7% of GDP in 2022 to 4.2% in 2024, with projections reaching 4.7% by 2025, making it one of NATO’s top military spenders. It’s important to note however, that while these increases coincide with U.S. pressure for burden-sharing, they also correlate with heightened security threats stemming from Russia’s invasion of Ukraine (Oleksiejuk, 2025). More broadly, defense expenditure rose across the alliance: the U.S. increased from 3.31% in 2022 to 3.38% in 2024, Germany from 1.51% to 2.12%, and France from 1.88% to 2.06%, signaling a broader shift in NATO’s strategic priorities (NATO, 2024).

For the Graphic: Graphic 2 (bar chart PLEASE NOTE FIGURES ARE INACCURATE, find real ones below)

2022 US - 3.31

2024 US - 3.38

—

2022 GERMANY - 1.51

2024 GERMANY - 2.12

—

2022 FRANCE - 1.88

2024 FRANCE - 2.06

—

2022 POLAND - 2.4

2024 POLAND - 4.2

The scolding from the U.S displayed faults in NATO’s deterrence credibility. When the U.S., the cornerstone of the alliance’s military power, shows uncertainty about defending its partners, adversaries like Russia may be emboldened to test NATO’s resolve, as seen in its continued aggression in Eastern Europe. Furthermore, the alliance’s ability to present a united front was compromised by intra-alliance tensions and rising political divisions, weakening the rapid coordination needed in a real-world military crisis.

Trump’s approach to NATO and broader foreign policy is a move away from traditional American leadership to strategic retrenchment. Historically, the U.S. played a central role in shaping and upholding multilateral institutions like NATO, positioning itself as a guarantor of global security and liberal democratic values. However, under the Trump Doctrine, this leadership gave way to a more inward-looking, transactional stance that prioritised national interests over collective commitments. While not full isolationism, this retrenchment recalibrated America’s global posture, and changed assumptions about its role as the linchpin of Western security structures.

4. The Future of International Peacekeeping and Multilateralism Post-Trump

The Trump Doctrine’s legacy, emphasising unilateralism, transactional diplomacy, and skepticism toward multilateral institutions, has left a lasting impact on the global order. As the United States swings between withdrawal and re-engagement under different administrations, the future of international peacekeeping and multilateral cooperation is uncertain. The post-Trump era will be shaped by three key factors: the durability of institutions like the UN and NATO, the growing influence of rival powers filling the void left by U.S. disengagement, and the unresolved debate over whether America will reclaim its traditional role as a global leader, a question that is especially dependent on which party wins the next election.

The United Nations and NATO have survived numerous geopolitical shifts, but the Trump presidency exposed their vulnerability when U.S. support wavers. While the Biden administration attempted to reverse some of Trump’s policies, including rejoining international agreements and reaffirming commitments to NATO, the long-term effects of distrust and reduced funding may persist (U.S. Indo-Pacific Command, 2021). UN peacekeeping missions, already struggling due to budget cuts and political marginalisation, now face existential challenges. Can they function effectively without consistent American backing? Some argue that reforms, such as fairer burden-sharing and clearer mandates, could strengthen these missions. However, without steady U.S. leadership, the UN risks becoming a market for geopolitical rivalry rather than collective problem-solving. Similarly, NATO’s future depends on whether European members can turn their talk of "strategic autonomy" into real military coordination, a goal complicated by political divisions and resource limitations.

The decline of U.S. leadership has allowed other major powers to expand their global influence. China, for instance, has increased its participation in UN peacekeeping, invested heavily in infrastructure projects worldwide, and strengthened its diplomatic presence in regions like Africa and the Middle East. Russia, meanwhile, has exploited NATO’s internal divisions and used asymmetric tactics to undermine Western initiatives. These trends suggest that multilateralism may not disappear but could instead evolve into a more fragmented system, where competing blocs pursue their own interests rather than upholding a unified global order. For smaller nations, this could mean navigating a world where they must balance relationships with multiple great powers rather than relying on U.S. protection.

The future of international peacekeeping and multilateralism ultimately hinges on the United States itself. The Trump Doctrine reflects a broader skepticism toward global engagement that existed before his presidency and will likely endure after it. Public opinion on foreign policy has become increasingly polarised, with Republicans favoring a more isolationist approach and Democrats supporting renewed international cooperation. This division brings in the question, can the U.S. maintain a stable global role if its citizens no longer see value in leadership? The answer will determine not only America’s electoral future but also the stability of the world order.

In the decades ahead, the international system may swing between a multilateral order led by a recommitted U.S., a fractured system dominated by regional powers, or a chaotic landscape where institutions weaken and conflicts escalate. The Trump era is demonstrating the risks of American disengagement but also the limits of multilateralism and unilateralism. Whether the world moves toward cooperation or division will depend on whether the U.S. and its allies can reconcile national sovereignty with the need for collective security, or whether the post-Trump era becomes defined by intensified great-power competition.