A string of measures taken almost simultaneously in European capitals points to mounting concern that the war in Ukraine could widen, or that Russia could probe the limits of NATO without launching a full-scale invasion, according to an analysis by CNN global affairs analyst Brett McGurk.

Belarus, Russia’s closest military ally, has held four days of exercises near its borders with Poland and Lithuania. Mechanised and armoured units trained in border protection and countering drones, among other tasks. Part of the drills took place close to the Suwalki Gap, a strip of land about 100 kilometres long that is the only land link between the three Baltic states (Estonia, Latvia and Lithuania) and the rest of NATO. Minsk described the exercises as defensive.

At the same time, French President Emmanuel Macron summoned political leaders and senior figures to the Élysée Palace for a confidential briefing from France’s intelligence services. Afterwards, Macron said the Russian “hybrid threat” against Europe and France had intensified. He called for a plan to better protect critical infrastructure and sensitive defence industry sites from drone and cyber-attacks.

En algunas cuentas ya se ha comentado pero es mejor mostrarlo con un mapa. El corredor de Suwalki, en territorio polaco, paso más corto entre Bielorrusia con Kaliningrado, siempre se ha considerado como el lugar de un posible inicio de conflicto en Europa. En realidad hay otro. pic.twitter.com/P3EqnS8VK8

— jpartej (@jpartej) September 19, 2026

Tusk warns of strikes disguised as accidents

Polish Prime Minister Donald Tusk was more specific. Addressing parliament, he said intelligence assessments suggested Russia could carry out hybrid strikes with drones or missiles on NATO countries that support Ukraine, then present them as “accidents”. Tusk said such a tactic could be designed to test allies’ resolve and to raise doubts over whether the alliance’s collective defence clause would be triggered.

Incidents in Baltic airspace have added to the unease. An Italian fighter jet on a NATO mission shot down a drone over Lithuania shortly after midnight on 15 September. The drone had entered from Belarus and, officials said, was likely carrying explosives. It was the first time a drone had been shot down over Lithuanian territory. Lithuanian authorities suspect it was Russian-made, but its exact route and purpose are still being investigated.

Why the Suwalki Gap is so critical

The gap, named after the Polish town of Suwalki, lies between Belarus and Russia’s Kaliningrad exclave. Poland and the rest of NATO’s mainland territory sit on one side, and Lithuania, with access to Latvia and Estonia, on the other. This geography has made it a fixture of the alliance’s defence planning scenarios.

The prospect that worries analysts most is not necessarily a large-scale Russian invasion, but a limited military move or another ambiguous operation. It would raise the political question of how quickly, and in what way, all 32 NATO members would respond.

NATO has repeatedly said an attack on any member would trigger its collective defence commitments, and it regularly holds exercises on its eastern flank. The existence of such scenarios does not in itself suggest Russia has decided to attack.

From sabotage to cyber-attacks

European concern centres on what is often described as a “grey zone” between peace and open war. It covers cyber-attacks, sabotage, arson, drone operations and strikes on critical infrastructure, all of which are harder to pin directly on a state and do not automatically prompt a military response.

On 15 September, the US Department of Justice announced charges against five people who, according to the indictment, worked for Russian intelligence services. American authorities allege the network planned attacks and assassinations in several countries, including the US, and was tasked with targeting civilian and military infrastructure in Europe. They also allege it plotted the murder of a Russian dissident in the US this summer. All five face charges of conspiracy to finance terrorism, and three of them also face murder-for-hire conspiracy charges. The suspects remain at large, and the allegations have not been tested in court.

The difficulty for NATO is that such operations can stay below the threshold of a conventional armed attack, leaving room for denial and for differing assessments among allies.

Hospitals, water, food and energy networks

Europe’s preparations now go well beyond weapons systems. For the first time, NATO has made public its updated baseline resilience requirements for 2026. Member states are asked to plan how governments, energy systems, telecommunications, transport, hospitals and supply chains would keep functioning during a crisis or armed conflict.

Particular emphasis is placed on food and water supplies, treating mass casualties, stockpiles of medicines and blood, restoring energy infrastructure and maintaining secure communications.

Ukrainian officials took part in the discussions, drawing on more than four years of experience in trying to keep essential services running under constant Russian attack.

Germany prepares its hospitals

In Germany, the debate has already reached hospitals and their ability to cope with large numbers of casualties in a military crisis. Military and health authorities are assessing infrastructure and emergency plans, and even reviewing the use of facilities built during the Cold War.

Britain calls for greater social resilience

In Britain, the government is stepping up its civil protection campaign and urging households to keep basic supplies, such as long-life food and water, in case essential services are seriously disrupted. The guidance is not aimed solely at a possible war. It covers a wider range of risks, from cyber-attacks and hostile acts to extreme weather and infrastructure failures.

Separately, Chief of the Defence Staff Air Chief Marshal Sir Richard Knighton, the head of the UK Armed Forces, has described the present period as the most dangerous of his 35-year military career.

Even Switzerland is changing its planning

Neutral Switzerland offers a striking example. The new national security strategy approved by the Federal Council, the Swiss government, on 18 September prioritises stronger resilience, protection against hybrid threats and the ability to defend the country. It sets out 10 objectives and 46 measures.

Bern assesses that a direct conventional attack on Switzerland remains unlikely for the foreseeable future. It notes, however, that the country could face long-range strikes, including by drones or ballistic missiles.

The American factor

Behind the heightened European activity lies the question of what role the US would play in any crisis.

US President Donald Trump said on 17 September that progress had been made in talks on a permanent US Army base in Poland, though no final decision has been taken. He credited Polish President Karol Nawrocki and said a location would be announced shortly if the plan goes ahead. To date, US forces in Poland have mostly been stationed on a rotational basis.

Separately, CIA Director John Ratcliffe travelled to Moscow at the end of August. According to US media reports citing people familiar with the talks, he warned the Russian side not to attack NATO territory.

The lesson from Ukraine

The main conclusion Europe is trying to draw from the war in Ukraine is that modern conflicts are not decided by the number of tanks, aircraft or missiles alone. They also demand power grids that keep running after strikes, hospitals able to absorb mass casualties, backup communications networks, transport that stays open and a state able to function for a long time under pressure.

That is the logic behind NATO’s new requirements. Political and social resilience is now treated as part of deterrence, and the alliance argues that the harder it is for an adversary to paralyse societies and state functions, the weaker the incentive to attack. McGurk argues that the surest way to prevent a wider war is to convince Russian President Vladimir Putin that it would fail.

The current activity does not mean a Russia-NATO conflict is seen as inevitable. It does show that European governments and the alliance now regard escalation beyond Ukraine’s borders as a more serious possibility, particularly through limited, hybrid or hard-to-attribute actions.

In that equation, the Suwalki Gap remains one of the most sensitive points on NATO’s eastern flank.