Wargaming the Effects of a Trump Presidency on NATO

Note: This wargame report featured in Business Insider, CBS News, and Rolling Stone:

Context

Donald Trump threatened to withdraw from NATO during his first term based on the idea that the US should not be defending Europe, whilst the Europeans under-invest in their own defence by spending less than the NATO agreed 2%. He has continued to do so in the run up to the 2024 elections. With specialists in defence, intelligence, foreign and security policy hailing from several NATO countries, a wargame was conducted to explore the following questions:

How might a Trump administration go about leaving NATO and/or getting all Allies to pay 2% GDP on defence?
What are the immediate consequences of the United States leaving Euro-Atlantic security to Europe?
What are the broader global consequences for the United States?

Business Insider

Rolling Stone

CBS News

Key Takeaways

The US fully exiting NATO is not realistic given the National Defense Authorization Act for the fiscal year 2024 is in place – The legislation states “The President shall not suspend, terminate, denounce, or withdraw the United States from the North Atlantic Treaty, done at Washington, DC, April 4, 1949, except by and with the advice and consent of the Senate, provided that two-thirds of the Senators present concur or pursuant to an Act of Congress.” Achieving this in the senate was considered highly unlikely by participants.

Despite Trump taking tangible steps to reduce the US commitment to defending Europe, Russia’s demands in Ukraine prevent it from realistically attacking a NATO Member.

If the US reduces its role in European security, it will likely damage investors’ sentiment throughout the continent, especially in Eastern Europe, thus damaging these state’s economies.

A US reduction in support to Ukraine makes the task of resisting Russia almost unfeasible, given Europe’s inability to adequately support Ukraine with what it needs.

A US policy of frustrating NATO has the potential to cause the alliance to collapse, with EU as a candidate for eventually replacing NATO’s ultimate function – defending Europe from Russia.

Trump’s proposed policies of punishment towards NATO will likely force Allies to spend more.

Timeline of Wargame Events

The wargame commenced on a successful Trump Inauguration Day: January 1, 2025, and running for two years into the presidency.

January 2025 – March 2025: Ukraine-Russia Peace Attempts

1. Trump’s US began by seeking to broker a deal between Russia and Ukraine, excluding major participation by any other states, although Turkey was privy to negotiations as they unfolded due to the Trump-Erdogan and Putin-Erdogan relationship. This caused serious fracture between the NATO QUAD (US-France-UK-Germany), and between US-Poland. Neither Ukraine nor Russia was willing to agree to concessional terms, so the war continued.

2. As threatened, Trump reduced Ukrainian aid to negligible amounts. Other NATO members, particularly UK, France, Germany, Finland, Sweden, Poland & Turkey agreed they would enhance support to fill some of the void.

April 2025 – June 2025: NATO Dormancy

3. It was only in March that the Trump administration was able to turn to developing its new policy towards NATO given the Russia-Ukraine negotiations. The administration realised that fully leaving NATO was not realistic, given the National Defense Authorization Act. Instead, the US decided to implement a policy of ‘dormancy’, as it was internally branded.

4. To deliver this policy, the US military and its representation in NATO was given instruction to:

• Create more ambiguous NATO warfighting plans, enacted by the NATO Supreme Allied Commander in Europe (SACEUR – who is always a US military official) in regard to an attack on a NATO member, not committing US assets in detail.

• Revoke powers given to SACEUR to act without political consultation at the North Atlantic Council.

• Reduce US participation in exercises.

• Reduce US intelligence sharing through NATO.

• Reduce US funding to NATO partnerships programmes.

• End US participation in the Nuclear Planning Group.

• End US participation in NATO’s nuclear deterrence mission.

• End the offering of US sovereign nuclear assets to protect NATO Allies.

• Redeploy 50% of US assets in Europe over 4 years, predominately to the Indo-Pacific.

5. Given that most NATO members on the frontline with Russia do meet the 2% target, states such as Poland, Finland, the Baltic States & UK sought to lobby the US to reverse these policies, promising to pressure low-spenders more. The US refused to reverse its new approach.

6. Given this reduced commitment to European Defence & Security, the Joint Expeditionary Force (JEF) began to prepare more forward leaning operations of deterrence and defence plans vis-à-vis Russia. The decision was also taken for JEF to enhance interoperability and dialogue with Poland.

July 2025 – April 2026: Adapting to US Dormancy in Europe

7. NATO Allies committed to spending 2% of GDP on defence at the Vilnius Summit in 2023. Two years on in this wargame, many Allies were still not, and US was vocal about it in the run up to the July 2025 summit. At the summit, low spending Allies committed to meet 2% spending by 2026, but these assurances did not nothing to placate the US.

8. Six months into US dormancy in NATO and the European theatre, Turkey and Hungary saw positive elements to the situation. Without US pressure, both sought to extract more self-serving concessions from NATO Allies by withholding consensus, as well as enhancing economic ties with Russia.

9. The Turkish administration strongly considered withdrawing from NATO in this period but chose not to given the assessment that US dormancy in NATO would not last beyond Trump. Turkish strategy was to keep US involvement in NATO on life support until post-Trump (January 2029). Turkey discussed its assessment with Allies. UK agreed it was only short-term, whereas France, Germany and Poland felt it was evidence that European Defence was now something that could not ‘be outsourced to US’.

10. France began pushing for greater collective defence via the EU, privately sharing with Germany that the ultimate goal should be to ‘subsume the role of NATO within EU by 2035’.

11. Despite 6 months of reduced US aid to Ukraine, the battlefield remained highly similar to how it did at the beginning of 2024. Having watched Trump’s dormancy in NATO for 6 months, Russia began thinking very seriously about a military operation to cut off the Baltic States from the rest of NATO using the Suwalki Corridor & Kaliningrad, achieving a fait d’accompli. The Russian rational behind such as strategy was to sow a ‘complete and final disunity’ in NATO given three Allies would be occupied, with no credible force coming to liberate them.

12. However, the Kremlin decided against it given the following constraints:

• The Ukraine conflict was still using much of Russia’s resources, so it could not open a second conflict on its border.

• That the US would not commit itself to defend Europe in full was still uncertain despite 6 months of dormancy.

• Russia assessed that the Baltic States could potentially resist an effective occupation, even without support from NATO.

• Russia assessed that the European NATO Allies could defeat Russia in the Baltic Sea & come to aid the Baltic States.

• Russia assessed that Finland and Poland alone, not to mention with support from other NATO Allies, possess the ability to counterattack into Russia, cut off Murmansk (Where Russia’s main nuclear deterrent and Northern Fleet are based), encircle Saint Petersburg, and have a path to Moscow.

• Russia risked becoming increasingly isolated globally by performing another ground invasion in Europe. 13.Russia deliberated on two possible outcomes to such an invasion:

• That it could divide NATO and bring about its dissolution at last, before a more pro-NATO President came in after Trump.

• That it could galvanize the Alliance, reinvigorate the US support for European Security, and drag Russia into a conflict that such an operation was originally designed to prevent. The latter was concluded as most likely by Russia, making an invasion of NATO soil highly unattractive

May 2026 – October 2026: Ukrainian Defeat

15. In May 2026 Russia launched a reinvigorated campaign against the Ukrainian defensive line. Given an absence of US support, and the inadequacy of EU (and UK/Turkey) support, Russia pushed the Ukrainian lines back, and by July 2026, Kyiv was encircled, with heavy shelling occurring daily.

16. Key NATO members such as US & Germany made it clear to Ukraine that membership was impossible whilst Russian forces occupied its territory.

17. With little choice, Ukraine agreed to a treaty signed in Ankara that:

• Recognised Crimea, Zaporizhzhia, Kherson, Kharkiv and the Donbass as Russian territory.

• Asserted that Ukraine will enshrine into law that it will never join NATO.

• Installed a Government in Kyiv that was pro-Moscow.

18. By May 2026 Poland had become a major military power with a highly regarded defensive & offensive capability. Poland felt a major frustration with the US and France, perceiving Paris to have ‘undermined support to Ukraine and the defence of Europe by opportunistically seeking to remove US from European Security Architecture and assert itself as the leading military power in Europe given its nuclear capability.’ Tension between Poland, France and Germany began to rise given the dwindling commitment to NATO by France, and indecision in Berlin on the future of NATO.

19. The UK was particularly worried that the nuclear umbrella of NATO had now been undermined, and 1.5 years into Trump’s administration, US withdrawal from nuclear co-operation still stood. The UK sought to encourage France to join the NATO Nuclear Planning Group and guarantee its nuclear assets to the protection of NATO, but Paris would not. Paris noted that one day it could foresee doing so through the auspice of EU.

November – January 2027: Closing the Wargame

20. In November 2027, the Trump administration and Russia began in-depth senior talks to repair their bilateral relations, end sanctions, and resurrect the broken security architecture between them. These talks were at CIA to FSB director level; National Security Advisor level; with plans for eventual Trump-Putin meeting.

21. By January 2027, US-China tension had worsened. The first 2 years of Trumps’ administration had seen:

• Increased incursions into Taiwan’s airspace.

• Increased tense moments between Chinese/US forces.

• Wider-ranging reciprocal sanctions.

• An assessment by US military that China’s ability to successfully take and hold Taiwan had increased, alongside the ability to deny US the ability to prevent it or reverse it.

22.A consequence of the US’s deteriorating relationship with Europe was that European states reduced their appetite to decouple from China economically.

23. After 2 years of Trump’s dormancy in Europe, NATO members (particularly those situated towards Russia’s borders) saw national and international companies reducing their presence, given the perceived increase in likelihood for a Russian invasion. This caused the continent to suffer economically, with reduced growth.

24. At time of writing in February 2024 (in the real world), the following Allies were above 2%:

In the wargame, by January 2027, the following had also achieved 2%:

France | Montenegro | Bulgaria | Netherlands | Norway

The following had made an above 0.3% increase:

Czechia | Denmark | Italy | Slovenia

Perceptions Outside the Euro-Atlantic

25. China saw the ‘US dormancy in NATO’ policy as clear evidence that US had now almost entirely turned its attention to containing it. It felt threatened and provoked by the lessening theatre simultaneity, with no ambiguity as to US full support should it invade Taiwan. China thus felt deterred.

26. Taiwan felt if Trump would reduce support to Ukraine and even the 75-year-old Alliance, it could happen to Taiwan. Taiwan felt it was necessary to increase investment in its own defence.

27. Japan, Australia and South Korea noted US increased focus on Indo-Pacific enhanced security in the region, but feared the whimsical ability of Trump to turn away from commitments.

28. North Korea believed the reduction in European focus was inevitable, and saw Trump’s approach as merely a fast tracked two-years in the pivot to the Indo-Pacific.

29. Israel felt the dormancy policy was expected and the right thing to do. It was not surprised to see the policy move low-spenders in NATO to spend more. Israel did not feel vulnerable to reduced US support given it was not relying solely on US umbrella.

30. Iran & Saudi Arabia felt it was evidence that the US was now unable to dominate several theatres at once. Thus, Iran felt it could exert greater influence in the Middle East. Saudi Arabia began rapidly increasing defence investment given it would have to take a greater role in checking Iran’s activity in the region