AS ORIGINALLY billed, the summit looked likely to be a humdrum affair. But a meeting of the NATO alliance in Newport in south Wales on September 4th and 5th, intended to mark the end of combat operations in Afghanistan, now looks likely to be one of the most important gatherings in the organisation’s 65-year history. From the moment in March when Russia’s president, Vladimir Putin, sent his troops into Crimea, thus beginning the first forcible annexation of territory in Europe since the second world war, it has been clear that NATO is back in the business it was created for: collective territorial defence.

Mr Putin has given NATO a shot in the arm just as its relevance was being questioned, and not for the first time. Although the alliance reached a peak of activity in 2011 with six operations in three continents (Afghanistan, Kosovo, Libya, a training mission in Iraq, counter-terrorism operations in the Mediterranean and counter-piracy off the Horn of Africa), most are now over or winding down. Russia’s military modernisation and menacing large-scale exercises close to NATO’s borders worried the alliance’s northern and eastern members. But most Europeans were more concerned about falling living standards than external threats to their security.

Even without the urgency added by Russia’s recent actions, NATO’s outgoing secretary-general, Anders Fogh Rasmussen, a former Danish prime minister, would have argued in Newport for European governments to halt the decline in their defence budgets, and to spend them more efficiently. But similar pleas in the past have fallen mainly on deaf ears. Just four of NATO’s European members (Britain, Estonia, France and Greece) come even close to meeting a commitment made in 2006 to spend at least 2% of GDP on defence, and only five have met another, equally important one to spend 20% of their budgets on modern equipment.

After the inconclusive results of 12 years of effort in Afghanistan, the era of large-scale military interventions far from Europe was thought to be over. A small American-led NATO residual force is likely to stay on for a few years to “train, advise and assist” the Afghan army in its continuing struggle against the Taliban (if security agreements can be signed quickly by Afghanistan’s new president). But despite the widening arc of instability across the Middle East and north Africa that followed the upheavals of the Arab spring and the rise of the jihadist Islamic State, addressing such complex threats through the creaking consensus-bound structures of NATO has seemed too difficult. The campaign in 2011 to remove Muammar Qaddafi from power in Libya, although successful in its immediate aims, exposed both divisions within the alliance and gaps in capability that fed America’s frustration with feeble European military spending. It also left behind an unholy mess.

As for America, new strategic guidance prepared for Barack Obama in early 2012 had complacently referred to “most European countries” as now being “producers of security rather than consumers of it”. It recommended taking advantage of a “strategic opportunity to rebalance the US military investment in Europe” towards Asia to meet the challenge of an assertive China. Re-energising an alliance that some in Washington believed was a relic of the cold war was low on the president’s list of priorities.

All that has now changed. Ukraine is not a member of NATO (indeed, preventing it ever becoming one is a principal aim of Russian policy) and therefore does not enjoy the protection afforded by Article 5, the vow taken by every member to regard an attack on one as an attack on all. But Mr Putin’s declaration of the right to take action wherever he believes the interests of Russian speakers are endangered directly threatens the Baltic states, which are members. Estonia, Latvia and Lithuania, which joined NATO in 2004, were part of the Soviet Union until its dissolution in 1991 and all have ethnic Russian minorities. After the seizure of Crimea, Mr Putin’s attempt to establish the Donbas region of eastern Ukraine as a Russian satrapy by fomenting and arming a separatist rebellion demonstrated the “hybrid warfare” techniques that the Kremlin might use to destabilise the Baltic.

The reaction to Mr Putin’s aggression has so far been mostly economic, with sanctions successively tightened. But it was immediately clear to Mr Rasmussen and the alliance’s leading military officer, the supreme allied commander in Europe (SACEUR), General Philip Breedlove of the US air force, that NATO would have to respond too. That meant providing immediate reassurance to the alliance’s most vulnerable frontline states, while getting all 28 members to agree on the nature of the threat to Europe’s security and the measures needed to counter it. It meant, above all, demonstrating that Article 5 remained the unshakable pillar of the alliance, at a time when doubts had been raised about whether, say, the Dutch or German governments would really send their troops to fight for Estonia or Romania.

Some of those measures have already been put in place. The air-policing operation over the Baltic states was quickly bolstered with additional jet fighters. Mr Obama visited Warsaw in June and announced a $1 billion package for stepped-up military exercises and training in eastern Europe, with additional rotations of American troops in the region (he will also make a symbolic stopover in Estonia before the summit). At about the same time, General Breedlove was asked by the North Atlantic Council, NATO’s political decision-making body, to develop a credible deterrent to Russian adventurism that could be put into action after the summit.

A potential problem for Mr Rasmussen was that even after the seizure of Crimea, NATO’s members had disagreed about the extent of the threat posed by Russia. Propaganda from Moscow about a spontaneous uprising that Russia only belatedly supported had seemed plausible to some; in Germany, history inclined many towards a policy of Russland verstehen—understanding, indeed sympathising with, Russia. Germany’s chancellor, Angela Merkel, born in the country’s communist east, has few illusions about Mr Putin but is rarely willing to get very far ahead of pacifistinclined public opinion. A naive new Italian government, acutely conscious of its fragile economy’s dependence on Russian gas, also hoped to avoid confrontation.

Setting the tripwire

NATO can only act by consensus, and some members feared that basing troops in Poland and the Baltic states would breach agreements reached with Russia in 1997 under the Founding Act, which formally declared an end to hostile relations. At a meeting of NATO foreign ministers in April, a call from Poland for 10,000 NATO troops to be stationed on its territory was rebuffed. Some did not want to hear Mr Rasmussen’s message that years of attempts by NATO to make Russia a strategic partner had failed, and that under Mr Putin Russia saw NATO only as an adversary.

But as evidence mounted of Russia’s engagement in the increasingly bloody insurrection in east Ukraine, the arguments of NATO’s doves seemed ever more feeble. The big shift in public opinion came in July, when separatist rebels shot down Malaysian Airlines flight MH17 with advanced weapons supplied by Russia. “Those clinging to an optimistic view of Russia had to recognise it had not worked; they had no answer,” says a senior NATO diplomat. The alliance must be prepared to deal with an antagonistic Russia for a long time, says Mr Rasmussen. “I would caution against thinking this is just about Putin. It is deeper-rooted in Russian society.”

The result is that General Breedlove is unlikely to face much political resistance to the deterrence package he sets out at the Newport summit. A “readiness action plan” has been drawn up with the aim of enabling NATO to respond rapidly to an Article 5 crisis. A compromise has been reached between those who think basing NATO forces permanently in the east and north of Europe, close to Russia’s borders, would breach the Founding Act, and those who argue that Russia’s own actions mean the act is already a dead letter: General Breedlove will propose pre-positioning command and control, logistics specialists, heavy weapons and ammunition, probably at an existing base in Szczecin in Poland (see map). The idea, he says, is to be able to “travel light but strike hard if needed”. The base is likely to be staffed on rotation, with troops from different member countries moving in and out. Frequent, large-scale exercises will signal NATO’s preparedness and maintain the crucial interoperability between national forces that was forged in Afghanistan.

An important element of the plans is to hold the newish NATO Response Force (NRF), which has 13,000 well-equipped troops provided on a rotating basis by members at its disposal, at a much higher state of readiness than before as the “spearhead” for the alliance’s future deployments. Within it a multinational force of brigade size (about 5,000 troops) will be deployable at the first sign of trouble, possibly within hours, on the order of the SACEUR without the usual requirement for consensual political approval.

The intention, says Mr Rasmussen, is to ensure that “any potential aggressor will know that if they are to attack one of our allies, they will not just meet national troops, but they will meet NATO.” The implication is clear: foes will have to reckon with a tripwire force that will trigger a response from the whole alliance. As one senior NATO official puts it: “There is extraordinary muscle memory in this organisation. We can still tool up pretty fast.”

A potential complication is that the hybrid warfare practised by Russia in Ukraine is more ambiguous than a conventional armed attack. General Breedlove says NATO must be ready for the “little green men”—special forces without sovereign insignia who cross borders to create unrest, occupy government buildings, incite locals and give tactical advice to separatists, thus destabilising a country. In an interview published on August 17th he told Germany’s Die Welt: “If NATO were to observe the infiltration of its sovereign territory by [anonymous] foreign forces, and if we were able to prove that this activity were being carried out by a particular aggressor nation, then Article 5 would apply.”

NATO may no longer be scrabbling about looking for a role, but Jens Stoltenberg, a former Norwegian prime minister who takes over from Mr Rasmussen in October, will still have to grapple with many of the same old problems that afflict the alliance. Mr Rasmussen says that ahead of the summit about half of NATO’s members have committed to no further reductions in defence spending, though that is, for many, a far cry from meeting their commitment to spending 2% of GDP. Nor, despite Mr Obama’s insistence that he sees Europe’s security as indivisible from America’s, is there likely to be much change in America’s strategic preoccupation with China. Mr Obama affects to see Russia more as a troublesome regional power than as a military and political rival like the Soviet Union of old. Whether NATO will play much of a role in Europe’s turbulent Middle Eastern back yard is also doubtful.

But for all its shortcomings, NATO retains an extraordinary ability to reinvent itself in the face of new threats. With enemies like Mr Putin, its continued relevance is not in doubt.