The UK announced this week that it would allow Kyiv access to classified technology to produce its own Storm Shadow (or Scalp) long-range cruise missiles, following reports that British drones were used in strikes into Russian territory.

A US intelligence report earlier this month warned that Russia could attack Nato within weeks, with the window of threat spanning until 2029. So what could that look like?

Minute one: The attack begins

Russia might spend months laying the groundwork with surveillance and reconnaissance missions, the movement of special forces into the area or setting up a political or diplomatic scenario to justify an occupation – but any military move would be swift.

Russia could move its northern fleet to seize the Svalbard islands quickly, or fly airborne troops into the Norwegian archipelago from northern Russia. The islands are undefended but strategically useful, with a Russian mining presence. Tensions over Svalbard have been rising in recent years, with Russia accusing Norway of militarising the islands. Weeks before the invasion of Ukraine, a major telecommunications cable from the mainland to Svalbard was cut, apparently by Russian vessels.

Another possible target is the similarly undefended Åland islands in the Baltic Sea close to Estonia, Sweden and Finland. The Finnish territory is demilitarised, partly autonomous and previously belonged to Russia. Vladimir Putin would probably deploy the 336th Naval Infantry Brigade based in Kaliningrad, or 76th Air Assault Division based in Pskov, Richard Hooker of the Atlantic Council said in a report earlier this year. This could happen with “little or no warning”, with these forces supported by commercial shipping or aircraft, and parts of the Russian Baltic Fleet.

Russia could also seize the Swedish island of Gotland in the Baltic Sea, giving it a greater foothold on a mostly Nato-owned coastline, and a gateway to defend St Petersburg.

Alternatively, Russia may decide to launch another land invasion in eastern Europe. Estonia, Lithuania, Latvia or Poland, which share borders with Russia, are all possible targets. In this scenario, Putin might send in a small military force – perhaps in plainclothes – to establish a separatist enclave within the Nato country, ostensibly in support of an oppressed Russian minority.

Russia could also attempt to build a land bridge to its territory of Kaliningrad, through Lithuania. It could mask the preparations as a military exercise, Hooker says, before launching ground troops from Russia or Belarus, accompanied by heavy ballistic missile strikes.

1-30 minutes: Information reaches allies

As the attack begins, Moscow might issue a public statement with a political justification for moving on the target territory, such as the oppression of Russians. When Russia invaded Ukraine on 24 February 2022, Putin appeared in a televised broadcast confirming the start of a “special military occupation”.

Otherwise, the first to discover any incursion into Nato would be intelligence analysts, who work 24/7 to monitor threats. In the UK, this is led by a secretive forces spy centre in Cambridgeshire and MI6 in London. Analysts would use information including satellite data, social media posts and human sources to compile urgent, classified reports which would be rushed up the food chain to inform decision-makers.

European leaders, including Andy Burnham, would be rapidly informed and pulled out of other engagements to work on the response.

An attack on any of Nato’s 32 members would be considered a direct hit on the UK, no matter where in the world it happens. This is because under the alliance’s Article 5, an attack on one member is considered an attack on all.

30-60 minutes: Emergency meetings

In the UK, an emergency Cobra meeting would be called, attended by the Prime Minister, Defence Secretary Wes Streeting and military chiefs.

Nato would call a joint meeting of all members to discuss a collective response. This would most likely be triggered by whichever country was attacked under the Article 4 provision, which allows for emergency consultation whenever a member’s “territorial integrity, political independence or security” is threatened.

Since the alliance’s formation in 1949, Article 4 has only been invoked nine times, four of these in relation to Russian aggression in eastern Europe. The UK would most likely be represented by the British ambassador to the alliance, Angus Lapsley.

The allies would then release a joint statement responding to the Russian attack and demanding withdrawal of Russian forces.

The attack could also set off shockwaves in the international economy, spiking oil prices.

60-120 minutes: The counter response begins

Nato’s military planners, working closely with national armed forces, would begin to devise their response. The scale and style of the Nato counter-operation would depend on the nature and location of the attack, but it has various top-secret battle plans in place.

In 2023, Nato approved defence plans that divide the alliance into three operational areas: the High North and Atlantic, which would be commanded from a base in Virginia; the central region covering the Baltic states, commanded from the Netherlands; and the south-east, covering threats along the Black Sea, commanded from Italy.

The UK would be expected to deploy troops and capabilities according to Nato’s plans. The British contribution would be led by the Chief Joint Operations at the military’s Permanent Joint Headquarters in Northwood, north-west London, who would turn Nato demands into a concrete military plan for all branches of the British forces.

The UK has a permanent presence of around 800 to 900 soldiers in Estonia and a few hundred troops in Poland under Operation Cabrit, set up in 2016 to defend Nato’s eastern flank. In the event of an attack in eastern Europe, insiders previously told The i Paper that the UK would be expected to reinforce its existing presence in Estonia, rather than immediately deploy troops to the site of the attack. The UK would want to ensure that Estonia was not vulnerable while attention was focused elsewhere as part of a Russian decoy or distraction.

The UK also has a range of elite, high-readiness units like the Special Forces, commandos and paratroopers who could be deployed to support Nato defences against an attack and arrive in theatre within hours.

Shortly after the attack, troops from across Europe could be mobilised and begin moving towards the site of the attack.

The British Army’s 4th Light Brigade, known as the Black Rats, is paired with the Estonian teams to provide back-up in case of emergency, offering specialist light forces who can fight in complex, varied environments, with one official suggesting this was the most likely unit to deploy in the case of a Russian attack. In May, 3,000 British forces led by the Black Rats deployed on an exercise to Estonia, arriving by road, rail, sea and air in under 48 hours.

The 16 Air Assault Brigade, the Army’s Global Response Force, could also be deployed and could send an initial advance party into theatre within two days.

The Royal Navy, which leads Nato’s Maritime Allied Reaction Force, might be deployed shortly after an attack. However, concerns have been raised about the Navy’s readiness to respond to threats, with a week-long delay before the warship HMS Dragon could set sail to Cyprus after it was hit by Iranian drones. The UK is also one of only three members to have nuclear weapons, and in the case of a serious attack, may move its nuclear submarines towards Russia.

The RAF, already deployed on air policing missions with Nato, would be expected to help protect against airborne attacks, either with more sorties or sending more jets and equipment. However, the UK would struggle to increase its contribution without cutting back elsewhere; it currently has Typhoon fighter jets deployed to the Middle East and requires jets to protect airspace at home. The RAF could increase its contribution to Nato’s Baltic Sentry mission, which gathers intelligence and carries out surveillance over the eastern flank.

Nato would not be the only side sending reinforcements. In the days after an initial attack, Moscow would send in additional military capabilities or civil infrastructure to support the occupying force and secure the territory.

On the Åland or Svalbard islands, Moscow might try to annex the territory, sending in national guard or border police troops, along with air defence, engineers, artillery, anti-ship missiles and electronic warfare units, Hooker said. In Eastern Europe, Russia would seek to legitimise its occupation with a mock government or sham referendum to prove support for integration into Russia, as has happened in parts of occupied Ukraine.

European countries could be hit by cyber attacks and disinformation campaigns in a bid to damage their resolve and ability to respond to the attack. In 2007, Estonia suffered a large-scale cyber attack lasting for weeks, which has been linked to Russia, though this has never been confirmed.

Melanie Garson, a professor of international security at UCL, said that commerce could be a key target. “The attacks on Wildberries and Ozon – Russia’s Amazon equivalent – would also place equivalent distribution warehouses for Amazon and similar throughout Nato countries on the frontline,” she said. “Malicious cyber activity within the supply chain, e,g, delivery partners, could also be an expected course of action.”

First week: Battle lines are drawn

Some of Nato’s military response might only arrive at the scene of the attack weeks after it has occurred.

The UK could deploy the Allied Rapid Reaction Corps, a high-readiness command post for Nato operations. Generally, High Readiness Force Headquarters must be ready to deploy their first elements within 10 days and the entire force within two months.

Hooker warned that Germany, France, Italy, and the UK cannot deploy a single division to Lithuania in less than 60–90 days, “far too slow to affect the outcome” of any attempt by Russia to build a land bridge to Kaliningrad, meaning Lithuania would be reliant on its own force to repel a Russian attack.

Ruben Stewart, a senior fellow at the International Institute for Strategic Studies, has cautioned about the logistical complexities for Nato in navigating multiple fronts and national boundaries for supply lines and troop movements.

These difficulties would be exacerbated by limits on defence spending, with low stockpiles of ammunition and drones, recruitment difficulties and capability gaps across Europe – all without the certainty of a US response, as Donald Trump’s White House turns away from European allies.

“Extensive fronts require commanders to balance forces, particularly shifting scarce assets between fronts,” Stewart said. “Europe faces resource constraints that would only be exacerbated by a major US drawdown.”

Should the attack expand into a full-scale war, the UK and other European countries may choose to call up reserve forces to bolster troop numbers – and prepare for a long fight.