Implications of the 2025 U.S. National Security Strategy for the UK and Europe

America’s 2025 National Security Strategy

A British view from the alliance front line

When the United States publishes a fresh National Security Strategy, Europeans tend to check the headlines, confirm that the transatlantic link still looks solid, and move on with their day.

This one is different.

The 2025 National Security Strategy (NSS) rips up a lot of the post-Cold War script. It declares that the days of the United States “propping up the entire world order like Atlas are over” and recasts alliances on far more transactional terms. It takes allies who have only just moved beyond the 2 per cent floor and locks in 5 per cent of GDP as the new expectation across the alliance, even though some front-line states had already signalled they were heading there. It goes on to question the trajectory of the European Union, warns of Europe’s potential “civilizational erasure”, and calls for an “expeditious cessation of hostilities in Ukraine” while pledging to end the idea of NATO as a “perpetually expanding alliance”.

From a European perspective, and especially from a British one, this is not just another Washington mood swing. It is a structural signal that the terms of the bargain are changing.

The question is not whether Europe can ignore it. It cannot. The question is how Europe chooses to respond.

A new transatlantic bargain: Security with strings attached

The core of the document is brutally clear. American foreign policy is to be driven by a narrow view of the “national interest”, under the banner of “America First”. Alliances are not abandoned, but they are no longer treated as quasi-sacred. Their value is judged against what they deliver for the United States.

On burden-sharing, the NSS signals a decisive shift. It positions the United States as no longer willing to underwrite the system alone. It suggests that advanced allied nations must step up, take regional responsibility, and contribute significantly more to collective defence.

The clearest sign of this shift is the Hague Commitment, which sets 5 per cent of GDP as the long-term spending benchmark for NATO members. The strategy presents this as a standard that allies have already signed up to and are expected to deliver. It is an extraordinary ask. For many European states, it would require more than doubling defence budgets that are already stretched by social, health and green-transition priorities.

From Washington’s standpoint, the logic is simple: allies that want American power behind them must contribute more and fall broadly in line with U.S. priorities. Those that do will find the door open to closer commercial ties, access to advanced technology and a smoother path on defence procurement. For those not able to deliver, they should expect a cooler, more transactional relationship. It is very much in keeping with the established Trump playbook.

For Europe, this creates three overlapping challenges:

1. Capability: how to translate rapidly higher spending into genuine military power, rather than duplicated programmes and political pork.
2. Cohesion: how to keep a 30-plus nation alliance together when front-line states see 5 per cent as existential necessity and others see it as fiscal suicide.
3. Consent: how to sustain public support for defence levels not seen since the Cold War, once the immediate shock of the Ukraine war fades.

From a UK vantage point, this moment offers both opportunity and responsibility. It has committed to the 5 per cent NATO pledge: under the new plan announced in June 2025, the UK aims to spend 5 per cent of GDP on national security, combining traditional defence, homeland security, and resilience measures.  That move positions the UK as one of the most politically able European states to meet the new standard, reinforcing its claim to lead within NATO. Embracing the 5 per cent target allows it to reaffirm its “special relationship” with the United States and cement its role as a key transatlantic partner.

The risk remains that, in some European states, especially where public support for rearmament is weak, a push for 5 per cent could come to be seen as Washington’s diktat championed by the most hawkish members of the alliance. If those divides deepen, cohesion could strain just when unity matters most.

Europe between autonomy and annexation

For two decades, Europeans have wrestled with the idea of strategic autonomy, the ability to act militarily without always waiting for Washington. The 2025 NSS, on the surface, pushes in that direction. It wants allies to assume primary responsibility for their regions, and effectively admits that the United States will not be omnipresent.

At the same time, the strategy levels heavy criticism at the very institutions that could organise European autonomy. It paints the EU and similar bodies as overly intrusive, politically constraining and ineffective on issues like migration, suggesting this has pushed Europe towards a worrying future. It urges a break from the regulatory mindset associated with Brussels and highlights the rise of nationalist movements as a sign of the course correction Europe should embrace.

This is not a neutral analysis. It is an ideological intervention in Europe’s internal debate. Washington is effectively saying: we want Europe to carry more of the security load, but we prefer that Europe be a loose constellation of assertive nation-states rather than an ever-more-integrated EU.

From the UK, that reads in two ways.

• On the one hand, the post-Brexit UK is comfortable with nation-state language and suspicious of over-centralised Brussels decision-making. The NSS’s emphasis on sovereignty, borders and national identity chimes with much of the UK political conversation.
• On the other hand, British security depends on an EU that is stable, predictable and functional. A United States that appears to side with polarising forces inside Europe risks deepening the very divisions Moscow has spent years trying to exploit.

For EU capitals, the impact is sharper still. Many will see the strategy as Washington aligning itself with their domestic opposition. That will not encourage deeper strategic intimacy.

So Europe faces a fork in the road. One option is to treat the NSS as a wake-up call and accelerate its own defence integration, while politely ignoring the ideological lectures. That would mean using the pressure of the 5 per cent target to push serious joint procurement, industrial consolidation and a Europe-first approach to critical capabilities. NATO would remain the core military framework, but European states would quietly ensure they can act together, if necessary, without always waiting for U.S. enablers.

The other option is to allow themselves to be pulled into Washington’s ideological project: framing the future of Europe primarily in terms of a culture war over migration, identity and Brussels’ reach. That might win applause in some quarters, but it would burn precious political capital that should be spent on concrete security issues: ammunition stockpiles, air defence, cyber resilience, and energy security.

Ultimately, Europe can seize this moment to build genuine strategic capacity, or allow itself to be swept into wider ideological contests that do not serve its long-term security.

Russia, Ukraine and the end of “perpetual expansion”

Nowhere is the NSS more delicate for Europe than with Russia.

The document deliberately stops short of portraying Moscow as a systemic adversary. It recognises that many Europeans view Russia as an existential threat, but frames that outlook as a consequence of Europe’s own strategic vulnerability rather than an American judgement. It states that a central U.S. interest is to secure a rapid end to hostilities in Ukraine, stabilise the broader European economy, prevent escalation or a widening of the conflict, and restore a degree of strategic stability with Russia, while ensuring Ukraine can endure as a viable state.

More broadly, it signals a shift in Washington’s view of NATO’s role in Europe. Rather than treating enlargement as an open-ended strategic principle, the strategy frames alliance expansion as something to approach with caution, particularly in the context of negotiating an end to the Ukraine war and re-establishing stability with Russia.

For Moscow, this is close to vindication of twenty years of complaints. Russia has long demanded a formal halt to NATO enlargement and a Western recognition of its sphere of privileged interests around its borders. For Kyiv, Tallinn or Warsaw, that same language is unsettling. It suggests that the open-door principle that brought them into NATO and underpins Ukraine’s aspirations is now a negotiable currency in a U.S.-Russia bargain - an approach already evident in the latest U.S.–Russian peace plans for Ukraine.

From a European perspective, there are two real questions.

First, the nature of any peace in Ukraine is far from clear. A rapid end to hostilities could take very different forms: it might amount to a ceasefire that entrenches Russian territorial gains and leaves Ukraine exposed, or it could be tied to credible withdrawal terms, security guarantees and a reconstruction framework. The NSS leaves that distinction deliberately vague. The initial U.S.–Russian draft agreement circulating in early December underscored the stakes. That 28-point proposal envisaged Ukraine accepting significant territorial concessions, limiting the size of its armed forces, ruling out NATO membership indefinitely, and agreeing to a demilitarised buffer zone, while offering Russia phased sanctions relief, reintegration into global markets, and even a path back to the G8. Although the plan has since been revised and remains under negotiation, the direction of travel is unmistakable. For European governments, particularly those on NATO’s eastern flank, the risk is that a premature settlement could reward aggression, freeze an unstable front line and create incentives for future salami-slicing elsewhere. For them, the ambiguity in the NSS is not a diplomatic flourish: it is a strategic hazard.

Second, there is the question of who actually sits at the table. The NSS depicts the management of European–Russian relations as a diplomatic task that will require heavy American involvement. That is understandable, given Washington’s leverage with both parties. Yet recent experience shows how easily Europeans and even Ukrainians can be pushed to the margins. Earlier peace proposals were circulated with only cursory consultation of Kyiv and minimal engagement with European capitals, despite the fact that Europe has borne the brunt of the conflict’s economic, humanitarian and security consequences. The early U.S.–Russian draft agreement made this uncomfortably clear: it presented a blueprint with far-reaching implications for European security architecture without meaningful European ownership. If a new settlement is hammered out primarily between Washington and Moscow, with Ukraine expected to acquiesce afterwards, Europe will find itself in the position of defending an accord it neither shaped nor fully supports. Worse, governments that have asked their citizens to shoulder high energy costs, increased defence budgets, and sustained political solidarity with Kyiv will be forced to justify a peace deal negotiated over their heads. That is a recipe for domestic backlash and strategic incoherence at precisely the moment Europe needs clarity and unity.

The UK has a particular role to play here. London has been one of Ukraine’s staunchest supporters and a consistent hawk on Russia. It can use that posture to insist that any eventual talks include clear red lines on sovereignty and accountability. At the same time, the UK will be under pressure from Washington to support a settlement that allows the United States to pivot away from Europe. Squaring that circle will require both clarity and honesty at home: explaining to British and European audiences what is being traded, and why.

The broader Russian question is this: does the NSS’s softer language help stabilise the European security environment, or does it risk entrenching the very dynamics that produced the war? A structured détente built around renewed arms control, transparency and mechanisms to prevent incidents would clearly serve Europe’s interests. A political freeze that normalises territorial revisionism and erodes NATO’s credibility would not. The gap between the two outcomes is narrow, and Europe has far more at stake than Washington in where the line is drawn.

The UK’s lane - lead, but do not subcontract

So, where does all this leave the UK? Three things stand out.

1. IT will be expected to lead by example. A UK that commits credibly to the 5 per cent trajectory, invests in its defence industrial base and demonstrates real capability gains will shape how the rest of Europe interprets the new strategic environment. London is well placed to help NATO shift from crude spending metrics to coherent capability portfolios: integrated air and missile defence, forward land presence, maritime patrol capacity, and the digital backbone of cyber and space resilience. That is a far more useful conversation than a league table of who has reached 5 per cent.
2. It needs to act as a bridge, not an enforcer. There will be a temptation in London to celebrate the NSS simply because it echoes long-standing British complaints about European under-investment. That would be short-sighted. The UK’s unique value is that it understands the political instincts of Washington and Brussels, as well as those of Warsaw, Paris, Rome and Berlin. If London leans too far into the role of Washington’s disciplinarian, it will lose traction in the very capitals whose decisions matter most. The real task is to translate American expectations into European-owned strategies rather than repeating U.S. ultimatums in a different accent.
3. It must keep Europe visible in Washington’s strategic field of view. The NSS leaves little doubt that, for the United States, the Western Hemisphere and Indo-Pacific will dominate attention in the years ahead. Europe is important, but no longer central. That drift will accelerate unless allies counterbalance it. A UK that stays closely plugged into U.S. strategic debates can help remind Washington of three enduring truths:

European crises have a persistent habit of drawing America back in, whatever Washington’s preferences. A united and capable Europe enhances rather than diminishes American power, and a settlement in Ukraine that Europeans can defend politically will always prove more durable than one negotiated over their heads.

What should Europe actually do?

Stepping back, there is a danger that European debates become absorbed in the surface drama of the NSS, the talk of civilisational decline, the arguments about defence spending, the media skirmishes over who offended whom in which summit corridor.

A more strategic European response needs to be quieter, steadier and more disciplined. It can be reduced to five practical points.

1. Spend more, but spend smart. Accept that higher defence spending is not a passing phase. Set multi-year trajectories that audiences can understand, then focus hard on closing fundamental capability gaps: stockpiles, enablers, readiness, resilience. If 5 per cent is politically unrealistic in some capitals for now, acknowledge that openly, but do not let it become a reason to avoid meaningful progress.

2. Integrate where it adds value. Use NATO to shape the military force structure and use the EU to coordinate finance, industry and regulation. Scale up joint procurement so Europe does not produce dozens of incompatible platforms for the same role, thereby forfeiting economies of scale. Preserve national flexibility, but stop fetishising it when integration would clearly deliver better outcomes. Of course, integrating Europe’s defence procurement is neither quick nor easy; it will demand sustained political will, harmonised requirements, and a willingness to accept that not every Armoured Fighting Vehicle or Next-gen aircraft will be built in a single country.

3. Keep the alliance two-way. If the United States expects more from Europe, Europe is entitled to expect clarity in return. That means transparency in Ukraine diplomacy, predictability in U.S. force posture, and genuine consultation before major policy shifts. Europeans should not hesitate to ask for this; maintaining cohesion is a shared responsibility.

4. Protect political cohesion. Defence spending is ultimately a political project. It requires taking Southern and Western European concerns about fiscal pressure seriously, just as it requires recognising Eastern Europe’s security fears. It also means resisting the temptation to turn every strategic disagreement into a culture-war symbol. Europe’s diversity is not a flaw in the system — it is an asset that must be managed with care and respect.

5. Plan for a more autonomous Europe, even inside NATO. Preparing for scenarios in which U.S. forces are focused elsewhere is not anti-American; it is prudent planning. Europe needs the command structures, logistics and political habits to conduct operations under a NATO flag or in coalitions of the willing when the United States is less engaged. The UK, France, Germany, Poland and others will all have essential roles to play in this.

A moment of choice

The 2025 National Security Strategy is not designed to reassure Europe. It reflects a U.S. strategic recalibration shaped by domestic priorities, long-term global competition and a desire to redistribute security responsibilities. It sets out an expectation that European states will assume greater liability for their own defence, accept that U.S. attention is increasingly directed elsewhere, and adapt to a diplomatic framework for Ukraine in which Washington plays a central role.

Europe now faces a choice.

One option is to respond defensively, treating the strategy as a challenge to established habits and thereby deepening divisions within Europe. That would reinforce the perception in Washington that Europe remains institutionally fragmented and strategically hesitant.

The alternative is to recognise that the structural shift underlying the NSS is unlikely to reverse. Europe can use this moment to consolidate its own capabilities, clarify its interests and approach the transatlantic relationship from a position of greater agency. This does not imply distancing from the United States. Instead, it means contributing more substantively to shared security while ensuring that European perspectives are built into emerging diplomatic and strategic frameworks.

For the United Kingdom, the implications are direct. A more capable and cohesive Europe enhances British influence within NATO and strengthens the UK’s position as a security actor with reach, credibility and diplomatic leverage. A weaker Europe, by contrast, increases the burden on London and narrows the set of partners ready to share responsibility for regional stability.

The NSS has altered the strategic landscape. How that landscape evolves will depend not only on decisions made in Washington, but also on those taken in London, Berlin, Paris, Warsaw and Rome in the period ahead.