The Triangle Alliance
Europe's three most powerful nations are constructing an unprecedented parallel security architecture to hedge against diminishing U.S. commitment under President Trump's second term.
The signing of the Kensington Treaty between Britain and Germany on July 17, 2025, represents the first bilateral defense pact between these nations since World War II, complementing the historic Northwood Declaration signed by Britain and France on July 10, 2025, establishing coordinated nuclear deterrence. Germany's Chancellor Friedrich Merz and Britain's Prime Minister Keir Starmer signed the Kensington Treaty covering defense, security, trade and migration, while France and Britain agreed to coordinate their nuclear arsenals for the first time. Germany's dramatic military expansion sees Chancellor Merz committing to 5% of GDP defense spending by 2029 - doubling from the current 2.4% of GDP (€95 billion annually). Merz advocated spending up to 5% of GDP on defense with 3.5% for military procurement and 1.5% for military-relevant infrastructure, while Germany plans to reach 3.5% by 2029.
This "triangle alliance" creates Europe's first nuclear coordination mechanism outside NATO while establishing joint weapons production and a Coalition of the Willing to support Ukraine as American backing potentially wanes.
Forecast Scenarios (GCHQ)
Likely (60-70%): Gradual Institutionalization with U.S. Accommodation
Over the next 12 months, the triangle alliance evolves into a permanent consultation mechanism complementing NATO structures, with the U.S. grudgingly accepting European strategic autonomy initiatives. Defense spending increases proceed on schedule, joint weapons programs advance, and the Coalition of the Willing expands. Trump administration rhetoric remains critical but stops short of threatening Article 5 withdrawal. Germany successfully implements initial defense spending increases while managing domestic resistance, and Franco-British nuclear coordination begins with intelligence sharing.
Realistic Possibility (45-55%): Accelerated European Integration Due to U.S. Disengagement
Escalating U.S.-Europe tensions over burden-sharing prompt faster triangle alliance institutionalization, expanding beyond bilateral agreements into trilateral frameworks. Trump administration signals explicit retreat from European security commitments, triggering accelerated European military buildup and potential discussions about extending French nuclear deterrence to Germany. The Coalition of the Willing assumes greater Ukraine support responsibility as U.S. aid diminishes, while European defense industrial cooperation expands rapidly.
Unlikely (25-35%): Triangle Alliance Fragmentation
Domestic political backlash in Germany against defense spending undermines Merz's fiscal plans, while Brexit-related tensions complicate British-EU defense cooperation. French political instability weakens Macron's European leadership, and the triangle alliance fails to institutionalize effectively. U.S. security guarantees prove more durable than expected, reducing European incentives for strategic autonomy, while economic pressures from defense spending generate political opposition forcing scaling back of military expansion plans.
