NATO, the oldest surviving collective security system, is facing challenge of transactional coercion from its own biggest member. What future does NATO have amidst such developments ?

NATO, founded in 1949 and the longest-surviving collective defence system, faces a threat its design never anticipated. Article 5 assumes external attack; the present strain comes from the ally on whose capabilities the guarantee actually rests.

The nature of the strain. The United States has recast the alliance as a transaction — protection conditional on payment — expressed through the burden-sharing dispute, doubts publicly raised about whether Article 5 would be honoured for members judged to be under-spending, and pressure over Ukraine policy. The 2025 Hague summit's commitment to raise defence spending towards 5 per cent of GDP by 2035, split between core defence and defence-related infrastructure, is best read as Europe purchasing continued American attention.

Why the damage is structural. Deterrence works on credibility, not capability alone. An adversary that believes the guarantee is negotiable has already gained, because Article 5 has never been about the ability to respond but about the certainty of it. Publicly conditioning that certainty devalues the asset the alliance exists to hold.

Three futures.

• Transactional continuity — the alliance survives as a paid service, with credibility permanently reduced.
• European strategic autonomy — the EU builds a defence pillar with real command, industrial and nuclear dimensions; slow, expensive and resisted by members who prefer the American guarantee.
• Coalitions of the willing — Article 5 formally intact but security delivered through bilateral and regional arrangements such as the Nordic and Baltic groupings.

Assessment. The likeliest path is the first, drifting towards the second. NATO's enlargement to include Finland in 2023 and Sweden in 2024 shows the demand for the guarantee is undiminished; what is in question is the supply. The alliance will endure institutionally while its deterrent value quietly declines, which is the more dangerous outcome because it is the harder one to notice.