If America Stands Back: NATO, Article 5 and the War Europe Could Be Forced to Fight Alone

AI-generated conceptual illustration. No real deployment, unit or incident is depicted.

A Russian operation begins below the threshold of conventional war: a suspected sabotage attack, a damaged communications cable, cyber disruption, a military incident whose origin is disputed. A deepfake appears online. Governments receive contradictory intelligence. Then people die, missiles appear on radar, Britain asks its allies for help — and Washington hesitates.

That is the central scenario in Sky's The Wargame, a four-part drama-documentary that places former senior politicians, military leaders and intelligence figures inside a simulated British national-security crisis triggered by a Russian attack. Sky says the scenario was developed with academics, military specialists and defence experts to make it as realistic as possible. ^[1]

The programme's most important question may not be whether Russia would attack Britain exactly as depicted. It is simpler: what happens if Europe discovers, at the moment NATO is needed most, that the United States does not intend to fight? The answer is more complicated — and in places more unsettling — than “NATO collapses,” because Article 5 does not work quite the way most people assume.

The North Atlantic Treaty contains one of the most famous sentences in international security: an armed attack against one member is considered an attack against them all. What follows matters enormously. NATO's own explanation states that once Article 5 is invoked, every ally has an obligation to assist the country attacked — but each state decides what action it “deems necessary.” That assistance does not have to mean troops; it can mean aircraft, intelligence, logistics, naval forces, cyber support, weapons or other measures, and NATO notes that allies may act unilaterally or bilaterally as well as through the alliance. ^[2]

NATO also operates by consensus. There is no majority vote that can overrule an objecting member; NATO describes its decisions as representing the collective will of every ally. ^[3]

Put together, this creates an important distinction. If the United States refused to participate militarily in the defence of Britain, Poland or the Baltic states, it would not hold a legal switch capable of stopping Britain, France, Germany, Poland, Finland, Sweden, Canada or others from defending one another. They remain sovereign states that could act individually, form a coalition, or coordinate outside NATO's formal political machinery. What American neutrality could paralyse is something different: NATO as the fully integrated military machine Europe has spent more than 75 years building around American power.

European NATO already fields formidable forces. Britain and France hold nuclear weapons; Britain, France, Germany, Italy, Poland, Finland and Sweden operate sophisticated air forces; and Europe collectively has submarines, frigates, destroyers, tanks, artillery, missiles, satellites, drones and hundreds of thousands of personnel. The shortfall is not weapons — it is what military planners call enablers: the systems that let large numbers of aircraft, ships and soldiers operate as one coordinated force.

The International Institute for Strategic Studies (IISS) identifies European dependence on the United States across satellite and theatre-wide intelligence, surveillance and reconnaissance, intelligence fusion, command and control, strategic airlift, aerial and logistical support, long-range precision strike, integrated air and missile defence, space capabilities, ballistic-missile warning, and the ultimate American nuclear deterrent. Its conclusion is that what Europe would lose most without the US is not raw numbers of tanks or aircraft — it is integration. ^[4]

Modern warfare depends on knowing where an enemy is, sharing that instantly, identifying targets, coordinating strikes and resupplying forces thousands of kilometres away. An army can own thousands of weapons and still lose if it cannot see, communicate, coordinate or resupply fast enough.

In 2025, IISS tried to price what replacing the American conventional contribution to European defence would actually cost. Its estimate: approximately $1 trillion — and money alone would not close the gap immediately. The study found Europe could face significant shortages in intelligence and surveillance systems, command infrastructure, air power, naval capability and several categories of advanced weapons if US forces withdrew, and that replacing the American contribution would mean replacing roughly 128,000 US military personnel associated with the European theatre under the scenario studied. ^[5]

The picture has improved since. NATO says European members and Canada increased defence expenditure by almost 20% in real terms during 2025, spending more than $571 billion at 2021 prices. ^[6] IISS estimates European countries accounted for more than 21% of global military expenditure in 2025, up from 17% in 2022. ^[7] At the 2025 Hague summit, NATO countries committed to eventually spending 5% of GDP on defence and related security — 3.5% on core defence and up to another 1.5% on infrastructure, resilience and cyber security. ^[6]

But weapons ordered today do not appear tomorrow. Factories need expansion, personnel need recruiting and training, satellites need launching, air-defence batteries need manufacturing, missile stockpiles need accumulating, and command systems need reorganising. IISS's September 2026 assessment concludes Europe has laid the foundations for a much stronger European pillar of NATO, but that defence self-reliance remains incomplete — and specifically that gaps in personnel, artillery, air defence, ammunition stocks, sustainment and readiness mean NATO's European members are unlikely to provide the complete backbone of continental conventional defence without American resources before 2030. ^[8]

Imagine Russian forces cross into Estonia, Latvia or Lithuania — the clearest Article 5 scenario. European governments would almost certainly consult immediately, and Poland, Finland, Sweden, Germany, Britain, France and others already maintain forces and defence plans for NATO's eastern flank. But without American participation, several problems appear fast: Europe would need to generate its own intelligence picture, coordinate hundreds of aircraft, provide extensive air and missile defence, and move reinforcements east through European railways, ports and roads while Russia tries to disrupt that movement.

The Baltic region is particularly difficult militarily. IISS describes Russia's evolving Baltic anti-access strategy as combining layered air defences, long-range weapons, electronic warfare, drones and reconnaissance systems designed to interfere with NATO reinforcement through the Baltic Sea and the Suwałki corridor between Poland and Lithuania. ^[9] Europe could fight — but not initially with the same integrated capability as a NATO force with full American participation.

This may be the harder problem. A power station explodes. A submarine cable fails. GPS systems stop functioning. A drone crosses a border. A cyberattack shuts down part of a banking system. An unidentified ship damages underwater infrastructure. Fabricated footage circulates claiming NATO attacked first. No single event necessarily reads as an obvious invasion — this is often called grey-zone or hybrid conflict, and it attacks NATO at exactly the point where Article 5 becomes difficult: attribution. Before governments retaliate, they need to establish who carried out the attack, and that takes time an aggressor can exploit.

European governments are already treating this as a live issue. IISS lists sabotage, UAV incursions and other unconventional activity as part of the threat currently facing NATO's eastern flank. ^[10] On 18 September 2026, Polish Prime Minister Donald Tusk publicly warned, citing intelligence assessments, that Russia could attempt drone or rocket attacks on NATO territory while presenting them as accidents — an allegation Russia would dispute and one that cannot independently establish future intent. ^[11] That is much closer to The Wargame scenario than divisions of tanks crossing a border.

Britain remains one of Europe's strongest military powers, with nuclear weapons, F-35 combat aircraft, submarines, destroyers, an aircraft carrier and capable intelligence services. But its own government acknowledges serious weaknesses. The 2025 Strategic Defence Review ordered the Armed Forces toward “warfighting readiness” and explicitly called for strengthening national resilience, ammunition stocks and the ability to defend UK territory — language that would not appear if the existing structure were judged sufficient for every foreseeable major conflict. ^[12]

The UK National Security Strategy identifies vulnerable critical infrastructure including power networks, transport systems, logistics hubs, data centres, telecommunications, energy pipelines and undersea cables. An extraordinary 99% of UK international data traffic travels through subsea cables. ^[13] A modern country can begin malfunctioning — payments, fuel, communications, energy — long before enemy soldiers arrive.

This may be more plausible than either full American participation or complete absence. Washington might provide intelligence but no troops; aircraft but no ground forces; missile defence without authorising strikes on Russian territory; help for one ally but not another; or delay while demanding negotiations. IISS argues American involvement is better understood as a spectrum than an on/off switch, with full involvement at one end, complete absence at the other, and partial, delayed or conditional support in between. ^[4]

That uncertainty has real consequences. Deterrence depends partly on an opponent believing retaliation will follow; if that belief weakens, an adversary may take greater risks. The same uncertainty can also restrain aggression, because the adversary cannot be certain an apparently reluctant America would never intervene. Potential opponents calculate what governments are likely to do — which is why alliance credibility matters as much as treaty wording.

As of 22 September 2026, the US has not withdrawn from Europe: a new troop rotation was just announced for Lithuania, ^[14] and Washington, Denmark and Greenland have agreed to expand the American presence in Greenland. ^[15] Reuters reporting this month describes the Trump administration's pressure on NATO, its reviews of troop deployments and its demands that Europe assume more responsibility as forcing European governments to examine how much they can keep depending on the US. ^[16]

For decades, British defence discussion concentrated on soldiers, aircraft, ships and nuclear weapons. A large interstate conflict would immediately involve something else: councils, hospitals, telecommunications companies, supermarkets, electricity networks, banks, transport companies and emergency services. A 2026 UK home-defence simulation called Exercise Grapple tested exactly this, involving local authorities, emergency services, military personnel, utilities and financial organisations in a scenario progressing from sabotage and cyberattacks to missile and drone strikes. It found Britain's existing emergency structures provide a useful foundation but that significantly greater coordination, integration and resilience would be needed under wartime conditions. ^[17]

Widespread electricity interruptions, unreliable card payments, congested mobile networks, delayed fuel deliveries, reduced port capacity, railways prioritised for military movement, hospitals on generators, and social media simultaneously carrying real information, misinformation, propaganda and psychological operations — the distinction between front line and home front begins to disappear.

Europe would not become defenceless without the United States, for one enormous reason: Britain and France are nuclear powers, so any state contemplating war against European NATO still has to consider nuclear escalation. SIPRI estimates approximately 12,187 nuclear warheads existed worldwide in January 2026, with about 4,012 deployed on operational forces and between 2,100 and 2,200 maintained on ballistic missiles at high operational alert; Russia and the United States together control the overwhelming majority. ^[18]

Britain and France hold much smaller arsenals, but nuclear deterrence is not simply a count of warheads — a force has deterrent value if it can survive an initial attack and inflict unacceptable retaliatory damage, which is what Britain's ballistic-missile submarines and France's independent nuclear force exist to do. SIPRI reports that Germany and other European countries have shown interest in discussing a larger British and French nuclear role, and that France began consultations on the subject during 2026 — though no agreed doctrine or public commitment currently exists. ^[18]

That raises an uncomfortable question with no available answer: at what point does a losing conventional war become a nuclear one, and who responds, and how? SIPRI warned in June 2026 that global dependence on nuclear weapons is increasing while arms-control structures deteriorate — all nine nuclear-armed states continued modernising their arsenals through 2025, and the New START treaty limiting American and Russian strategic weapons expired in February 2026 without a successor. SIPRI describes rising risks of escalation and miscalculation as a result. ^[18]

Would NATO collapse if America refused to fight? Not automatically — that is the most important factual distinction to take from the scenario. America cannot legally stop other NATO members defending one another; Britain, France, Poland, Germany, the Nordic countries and Canada could still fight, individually or as a coalition outside NATO's normal machinery, and European forces collectively hold substantial conventional power. But a neutral America would remove or reduce many of the systems that power has been organised around. The immediate problem would not be “Europe has no army” — it would be whether dozens of national militaries can be turned into one coherent warfighting system quickly enough. The evidence suggests Europe is moving rapidly in that direction, but the transition remains incomplete. ^[8]

Nor has America abandoned NATO: forces remain deployed, new deployments continue, and Washington stays deeply integrated into NATO's military structures. ^[14] But the assumptions underneath European security are visibly shifting — rising defence spending, rebuilt ammunition stocks, accelerated air-defence investment, protected energy and subsea infrastructure, Britain's explicit move to warfighting readiness, and open European planning for reduced American support. Those changes are not being made because a television drama imagined an interesting plot; governments are responding to a security environment they judge has materially changed.

Article 5 remains extraordinarily powerful, but it is ultimately words on paper implemented by sovereign governments, and its power comes from the credibility behind those words — aircraft that can fly, missiles that exist in sufficient numbers, satellites that can find targets, ships that can deploy, armies that can mobilise, factories that can replace what is destroyed, civil infrastructure that can survive attack, and governments willing to act when acting carries a real price. If Article 5 is ever tested by a major power, the question will not be whether the treaty contains the right words — it will be whether 32 governments still believe those words are worth the cost of enforcing them. ^[2]