The NATO Secretary General, Mark Rutte, has urged the UK government to establish a “credible path” with “yearly steps” to increase its defence spending to meet new alliance-wide objectives.
Speaking during a visit to the United Kingdom on 16 September, Mr Rutte called for allies to work towards a core defence spending target of 3.5% of GDP by 2035. The demand comes as NATO seeks to bolster its collective security and warfighting readiness in response to long-term threats from Russia.
The NATO chief met with Prime Minister Andy Burnham at the Harwell Science and Innovation Campus. During the discussions, Mr Rutte emphasised that meeting the alliance’s capability requirements would necessitate consistent, incremental budget increases rather than back-loading spending towards the end of the decade.
The £30 billion challenge
Current UK government projections show defence spending reaching 2.7% of GDP by the 2027/28 financial year. Moving from this level to the 3.5% target advocated by NATO represents a significant fiscal challenge, with independent estimates suggesting a funding gap of approximately £30 billion.
The push for higher spending follows the 2025 Strategic Defence Review (SDR), which established a “NATO First” priority for British forces. This policy shift was intended to ensure that UK military procurement and personnel numbers are aligned with the alliance’s frontline requirements in Europe.
The request for increased funding places pressure on the Treasury, now led by Chancellor John Healey. Mr Healey, who was appointed to the role in July 2026 following the change in administration, previously resigned as Defence Secretary under the former government specifically over concerns regarding military funding levels.
National security priorities
The government has not yet confirmed whether it will commit to the 3.5% target or how such an increase would be financed. Official options for meeting substantial defence increases typically involve a combination of taxation, further borrowing, or spending reductions in other government departments.
NATO leadership has argued that the previous guideline of 2% of GDP is no longer sufficient to maintain a credible deterrent. While the UK has consistently met the 2% floor, Mr Rutte indicated that the “credible path” must show clear, annual progress to reassure international partners of Britain’s long-term commitment to European security.
The government has maintained that it remains committed to its target of 2.7% of GDP by 2027/28, a milestone originally set in February 2025. However, the new pressure from NATO suggests that the UK’s military budget will remain a central point of debate as the government prepares for its next major spending review.
