At the Nato summit in Madrid this week sweeping changes to the western military alliance were agreed by leaders, including a huge increase in the number of troops deployed in Europe.

About 300,000 troops across the continent will be placed at high readiness from next year in case Russia threatens a military attack on any member of the alliance, and Finland and Sweden will be formally invited to join.

Extra forces to be allocated specific allies to defend

Existing Nato defences on the alliance’s eastern flank will be increased to the size of a brigade – about 3,000 to 5,000 troops in addition to local forces.

Britain will commit an extra 1,000 UK-based troops and one of its two new aircraft carriers to the defence of Estonia, where Britain already has about 1,700 personnel deployed. Joe Biden, the US president, announced the stationing of a brigade of 3,000 combat troops in Romania, two squadrons of F-35 fighters in the UK and two navy destroyers in Spain.

Heavy equipment positioned near borders with Russia

Jens Stoltenberg, the Nato secretary general, explained that the new strategy meant heavy equipment would be positioned near Nato borders, with the ability to rapidly move people into place to use it. Before the summit, Estonia’s prime minister, Kaja Kallas, had claimed that existing Nato defence plans would give Russia the time to wipe Tallinn off the map before western troops could be mobilised. During the summit, the UK defence secretary, Ben Wallace, admitted it would have taken 60 days to move extra tanks to the Baltic states in the event of a conflict under the old plans.

Russia identified as main threat to Nato

A 2022 Nato strategic concept document was published, which identified Russia’s invasion of Ukraine as the driving force behind the changes. It was the first time the document had been revised since 2010, when Russia still attended Nato summits. It states: “The Russian Federation’s war of aggression against Ukraine has shattered peace and gravely altered our security environment. Its brutal and unlawful invasion, repeated violations of international humanitarian law and heinous attacks and atrocities have caused unspeakable suffering and destruction.”

Finland and Sweden formally invited to join

A deal agreed between Finland, Sweden and Turkey cleared the way for the formal invitation of the two Nordic states into the alliance. That signalled the end of the two countries’ traditional neutrality, which dated back to the cold war – and in Sweden’s case before that. Turkey’s objections were dropped after reaching a deal in which the two Nordic countries vowed to take steps to control support for Kurdish terrorism. Their membership has to be ratified individually by the parliaments of all 30 existing allies.

Defence spending

Nato’s target that 2% of GDP of each country be spent on defence will in the future be seen as “more of a floor than a ceiling” said Stoltenberg. But although Downing Street agreed the 2% target was outdated, it said there needed to be a “reality check” on existing commitments to spend above inflation every year in the parliament. Wallace, however, called for greater investment after 2025. “As the threat changes, so must the funding,” he said.

An eye to China

The Nato document states that China’s “malicious hybrid and cyber operations and its confrontational rhetoric and disinformation target allies” and that China’s “stated ambitions and coercive policies challenge our interests, security and values”. The leaders of Australia, Japan, New Zealand and South Korea attended a Nato summit for the first time.