When allied leaders converged in The Hague in June 2025, they celebrated a headline commitment: a collective defense-spending benchmark of 5 percent of GDP by 2035. The formula — 3.5 percent allocated to traditional hard defense and 1.5 percent described as a resilience component — was designed as a political compromise to broaden buy-in across capitals. Nearly five months on, however, the resilience pillar has emerged as the most consequential loose end.

The problem is stark and procedural. The summit declaration provided no definitions for what counts toward the 1.5 percent, no annex listing eligible expenditure categories, no independent oversight mechanism and no common reporting standards. The first progress check in the declaration is scheduled for 2029, leaving a sizeable reporting and verification gap during which accounting choices will shape narratives about burden-sharing and capability building. Without guardrails, the 1.5 percent pillar will invite creative accounting and undercut the credibility of the entire spending pledge.

Resilience is, in principle, a legitimate and necessary dimension of modern deterrence. Investments in energy security, civil infrastructure, cyber defense, logistics hubs, and population resilience blunt the effects of hybrid campaigns and sustain a military response. But resilience budgets straddle civilian and military domains; national accountants and ministries of finance may be tempted to reclassify routine civic spending as security investment in order to meet political commitments without reallocating defense budgets.

The diplomatic stakes are high. Allies that meet or exceed hard-defense targets will rightly seek assurance that the broader metric is not diluted by across-the-board rebranding of non-defense outlays. For capitals such as Washington, whose domestic politics increasingly condition security assistance on demonstrable allied burden-sharing, perceived loopholes could weaken congressional support for forward forces and munitions funding. For newer members and those facing immediate regional threats, a robust and transparent framework is essential to ensure resources translate into usable capabilities rather than paper compliance.

NATO now faces a narrow window to convert the Hague compromise into enforceable practice before leaders reconvene in Türkiye in 2026. Practical measures are available without reopening the political bargain: agreed accounting standards, a catalogue of eligible resilience categories with thresholds tied to verifiable outputs, interim reporting templates, and a peer-review mechanism overseen by NATO’s secretariat. Such steps would both preserve the political consensus that produced the 5 percent target and harden its operational value.

Failing to act risks a double erosion: diminished deterrent effect vis-à-vis adversaries testing alliance resolve, and fraying trust within the alliance as members accuse one another of gaming commitments. The resilience pillar was meant to be a force multiplier; absent clarity and oversight, it may instead become the weak seam that unravels the collective promise. The Hague bought time — now the alliance must use it to build rules that make the pledge real.