NATO Secretary-General Mark Rutte has welcomed Britain's new Defence Investment Plan, positioning it as a critical milestone in the alliance's push to reach 3.5% of GDP in core military spending by 2035. For observers in Portugal—where defence expenditure now sits at approximately 2% of GDP—the UK announcement illustrates the scale of the financial commitment expected from all NATO members and foreshadows the budgetary pressures Lisbon may face in the years ahead.
Why This Matters
• Portugal is now obligated under the 2025 Hague Summit agreement to reach 5% of GDP in total defence and security spending by 2035 (3.5% direct military, 1.5% resilience).
• Britain's £300 billion (€348 billion) four-year plan sets a benchmark for what "credible" defence modernization looks like—and underscores the gap between current Portuguese military capabilities and NATO expectations.
• The Ankara Summit (7-8 July) will formalize procurement contracts worth tens of billions and assess each ally's spending trajectory, including Portugal's.
• Strategic autonomy vs. transatlantic reliance: Britain's pivot toward drones, cyber, and next-generation fighters signals where future NATO funding will flow—and where Portugal must invest to remain interoperable.
The British Commitment Decoded
Britain's Defence Investment Plan commits over £15 billion (€17.4 billion) in additional spending over four fiscal years (fiscal years run April-March in the UK), pushing direct military expenditure to 2.7% of GDP by fiscal year 2027-28 and 3% by the next parliamentary term. When infrastructure, energy security, and critical supply chains are included—categories now counted under NATO's updated methodology—the UK's total effort reaches 4.2% of GDP, edging close to the 5% target all allies pledged to hit by 2035.
That £300 billion envelope will fund £5 billion in autonomous drones and unmanned systems, £8.6 billion for the Global Combat Air Programme (a trilateral fighter jet with Italy and Japan), £2.5 billion for cyber and electromagnetic warfare, and more than £63 billion to sustain and modernize Britain's nuclear deterrent. Long-range missiles, integrated air and missile defence, and armoured-vehicle renewal round out the portfolio.
Rutte, who met with UK Prime Minister Keir Starmer at Downing Street this week, called the plan "a good step" and noted that a "stronger British defence makes the entire NATO safer." The timing matters: Britain will attend the Ankara Summit—scheduled for 7-8 July in Turkey—ready to showcase procurement contracts and production timelines, putting pressure on allies who have yet to translate pledges into funded programmes.
What This Means for Portugal
For Portugal, the UK plan is both a blueprint and a warning. Under the Hague commitment, Portugal must eventually allocate roughly 5% of national GDP to defence and security. In 2025, Portuguese military spending stood at approximately 2% of GDP—enough to clear the legacy 2% floor but a long way from the required 5% target.
Scaled to Portugal's economy, meeting the new 5% target would require substantial additional funding. Portugal's 2024 GDP was approximately €270 billion. Moving from the current ~2% to 5% would require an additional €8 billion annually by 2035. However, reaching the core 3.5% military spending target (from current ~2%) would require approximately €4-5 billion in new military spending annually, with the remaining 1.5% allocated to resilience and security infrastructure.
That sum would exceed Portugal's entire public-health capital budget and would demand politically contentious trade-offs: pension reforms, higher VAT on certain goods, or reductions to education and social services. This could translate concretely to cost increases on everyday items like food and fuel, adjustments to retirement benefits, or reduced funding for schools and hospitals. Alternatively, Lisbon could raise income taxes—a politically difficult choice in a country where the tax-to-GDP ratio already exceeds 34%—or renegotiate EU fiscal rules to carve out defence spending from deficit calculations.
Yet failure to comply carries strategic costs. Portugal hosts NATO Air Policing detachments, planning cells linked to allied command structures, and controls critical Atlantic choke points. If allies perceive Lisbon as a free rider, Portugal risks losing influence over alliance posture in the Mediterranean and the Atlantic archipelagos of Madeira and the Azores, which anchor NATO's southern flank.
The Portuguese government has not yet announced a detailed roadmap for reaching the 5% target, leaving uncertainty about which approach—tax increases, spending reallocation, or EU fiscal negotiations—will be pursued. This remains a contentious domestic issue, with civil society and opposition parties questioning whether military spending should take priority over social investment.
Where the Money Will Go
The UK's spending priorities reflect lessons learned in Ukraine. Drones and loitering munitions—proven force multipliers in Donbas—will receive £5 billion over four years. Britain has already committed £3.75 billion in military aid to Kyiv this year, including more than £500 million for air-defence systems and £150 million toward NATO's Priority Procurement List, which channels urgent materiel directly to Ukrainian batteries.
Cyber resilience and electromagnetic warfare—domains in which Russia has tested NATO infrastructure through sabotage, signal jamming, and disinformation—account for £2.5 billion. Britain is also leading two new NATO missions: one in the High North and Arctic (where ice retreat opens contested sea lanes) and another in the Strait of Hormuz, ensuring energy flows from the Gulf.
For Portugal, the message is clear: future NATO credibility hinges on high-tech interoperability. Legacy platforms—patrol vessels, ageing F-16s, and pre-digital command systems—will increasingly fall outside alliance planning. Portuguese defence planners must either invest in next-generation capabilities or risk being sidelined in joint operations.
The Ankara Summit and the 5% Commitment
When NATO leaders convene in Ankara on 7-8 July, the agenda will centre on production capacity, burden-sharing, and contract announcements. Member states are expected to present concrete procurement timelines demonstrating how they will reach 3.5% core spending and 1.5% resilience investment by 2035.
According to 2025 spending data (published in 2026), Poland leads the alliance at 4.48% of GDP, followed by Lithuania (4%), Latvia (3.73%), and Estonia (3.38%). The United States spends 3.22%, while traditional European powers lag: France at 2.05%, Germany at exactly 2%, and Spain only recently crossing the 2% line. Portugal's spending at approximately 2% of GDP places it in a middle position but well short of the new standard.
Mark Rutte has framed the Ankara gathering as a litmus test: allies must show they are converting "economic power into military capability." That language targets wealthy member states—Germany, Italy, Spain—whose industrial bases could sustain higher output but whose defence ministries remain underfunded. Portugal, with a smaller economy and limited domestic defence industry, faces a different bind: it must import most capabilities while balancing a debt-to-GDP ratio still above 100%.
Political Headwinds in Britain—and Lessons for Lisbon
Britain's Defence Investment Plan has not sailed through unopposed. Some defence analysts and former officials have raised concerns that the funding envelope, while substantial, may prove insufficient to simultaneously meet NATO commitments, fund modernization initiatives, and address maintenance backlogs. Critics warn that Britain risks repeating the "hollow force" phenomenon of the 1990s: ambitious capability targets funded by optimistic growth assumptions and deferred maintenance.
Portugal's political class should heed that caution. Announcing a glide path to 5% of GDP without identifying credible revenue sources or cutting less-critical programmes invites fiscal instability. The Portugal Council of Ministers will need to present a credible multi-year plan—likely in the 2027 state budget—that reconciles NATO obligations with domestic priorities. That plan may include joint procurement with Spain, EU defence-fund leverage, or private-sector partnerships to build maintenance hubs in Portuguese ports and airbases.
A New Transatlantic Bargain
Britain's pivot also reflects a broader strategic shift: building "a more European NATO" without abandoning the US security guarantee. London is betting that greater European capability will reassure Washington, discourage American disengagement, and preserve the transatlantic link even as European allies shoulder more operational burden.
For Portugal, that shift is double-edged. On one hand, a "Europeanized" NATO could channel EU structural funds toward dual-use infrastructure—ports, railways, digital backbones—that Portugal desperately needs. On the other, it demands that Lisbon field credible forces for regional contingencies, from North Africa to the Baltic, rather than relying on American airlift and enablers.
The Bottom Line
Britain's £300 billion Defence Investment Plan establishes a new floor for serious NATO membership. By 2027-28, the UK will rank as the alliance's third-largest defence spender by absolute value, trailing only the United States and Germany. For Portugal, the plan is a preview of the budgetary reality ahead: 5% of GDP by 2035 is not rhetorical aspiration but binding commitment, and Ankara will be the first checkpoint.
Portuguese policymakers must now decide whether to frontload investment—capturing efficiencies and industrial partnerships early—or defer painful choices until the decade's end, risking both fiscal shock and strategic irrelevance. Either way, the Hague pledge has moved from summit communiqué to balance sheet, and the bill is coming due.
