NATO’s pledge to move toward spending 5 percent of gross domestic product on defence by 2035 — 3.5 percent on core military capability and a further 1.5 percent on related security — has entered its least comfortable phase: the years in which communiqués must become budgets, according to reporting on alliance spending plans following the Hague agreement.
The arithmetic explains the discomfort. Only a handful of allies currently spend at the 3.5 percent core level, according to the figures cited in coverage of the pledge, while the alliance average remains well below it. For the United States, which already spends above the core threshold, the pledge is principally a burden-sharing instrument: Washington’s argument, pressed for years under administrations of both parties, is that European and Canadian allies must fund a larger share of the continent’s conventional defence so American forces can cover global commitments without hollowing out any single theatre.
The 1.5 percent “related security” component is where definitions will be fought over. Infrastructure that moves armies — rail, ports, bridges rated for armour — cyber defence, energy resilience and protection of undersea cables can all be argued into the category. Allies are expected to submit credible annual paths toward the target, and the credibility test will be whether finance ministries, not only defence ministries, sign the trajectories. A pledge that lives in a summit declaration but not in a medium-term budget framework is, in fiscal terms, still a wish.
Russia is the stated reason for urgency. Alliance planning, as reported, works to a warning horizon around 2030 for a possible major confrontation if Moscow reconstitutes its forces after the Ukraine war while European rearmament lags. That timeline is why the spending debate has shifted from percentages as political signals to production as physical fact: artillery ammunition, air defence interceptors, drones and the industrial lines behind them. Money voted in 2026 becomes delivered capability in 2028 or later, which is precisely why the alliance wants the budget ramps started now.
Turkey’s framing at the Ankara discussions — a stronger Europe inside a stronger NATO — captures the compromise being attempted: European allies build more, the United States remains the alliance’s backbone, and the new spending is presented as complementing rather than replacing American power. Whether voters across 32 democracies sustain a decade of rising defence budgets through elections, housing crises and welfare pressures is the unanswerable question inside the pledge.
For American readers, the metric to watch is not the 2035 headline but the 2026–27 budget laws: how many allies legislate a rising path, how much of the increase is core capability rather than reclassified spending, and whether joint procurement turns national ramps into interoperable forces. The pledge has supplied the destination. The next alliance argument will be about the slope.
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