Nato generals and officials have good reason to be grateful to Vladimir Putin. Struggling to find a role for the 28-member alliance since the end of the cold war, Russia's actions in Ukraine have provided the moribund and unwieldy organisation with an opportunity to reinvent itself.

The big question at the two-day Nato summit that begins in Wales on Thursday is whether Nato will take the opportunity on offer or continue to slide into irrelevance.

Describing the summit as crucial, Nato's secretary general, Anders Fogh Rasmussen, talked up at a Brussels press conference on Monday various plans for confronting the Russian threat. Top of his list, to be agreed at the summit on Friday, is a Readiness Action Plan (RAP), which includes a 4,000-strong rapid-reaction force to be deployed within 48 hours of a Russian incursion into a member state.

Reflecting scepticism about how effective such a tiny force would be in confronting the Red Army, journalists at the press conference joked afterwards with Nato officials that the commander of the new force would be known as CRAP.

But there is a serious issue behind the joke. Is there a real willingness, in the aftermath of Iraq and Afghanistan, for the member states to face up to Russia? Nato has made it clear that it does not intend to become involved militarily in Ukraine and has only scheduled a symbolic meeting at the summit with the Ukrainian president, Petro Poroshenko. The more pressing question for the summit is whether there is enough resolve within Nato should Putin begin to create unrest in one or more of the Baltic states.

Robin Niblett, director of Chatham House, said: "The Nato summit is taking place at a time of a perceived decay in western international leadership." The est was being tested not only by Russia but China and non-state actors such as Islamic State (Isis) in Iraq and Syria, believing that the west had been weakened, not only by Iraq and Afghanistan and the world financial crisis. This was visible in a host of decisions by the US and its allies in recent years, he said.

"The question is whether President Putin's action in Ukraine and IS's excesses in Iraq will actually help the west coalesce again for the first time since the end of the cold war around a shared sense of security threats they confront," said Niblett. "The Nato summit is the test."

Niblett is optimistic that it will prove to be "the beginning of a turning of the corner in western security outlooks".

The main message from the summit will be an attempt to reassure nervous Baltic states, which, unlike Ukraine, are members of Nato, meaning the other members are obliged to come to their aid in the event of Putin deploying the same tactics as he did in Ukraine.

British troops during exercises in Poland. Nato plans to create a 4,000-strong force to be deployed within 48 hours of a Russian incursion. Photo: Mark Nesbit/MoD/EPA

Tate Nurkin, director of Jane's Strategic Advisory Services in Washington, described Putin's tactics as unconventional: part bullying, part proxy conflict, part propaganda and part invasion, but not full war. "To Nato members bordering Ukraine and Russia it was also an approach for which Nato was worryingly unprepared and, of much more alarm, an approach that could plausibly be replicated in states with large Russian minorities, particularly Latvia, Lithuania and Estonia."

That is where, theoretically, the Nato rapid-reaction force would come into play. In the unlikely event of a full-scale invasion by Russia of the Baltic states, it would place multinational forces alongside the national force and presumably make Russia think twice about engagement. Such a force might prove less relevant when faced by the kind of unconventional tactics similar to those used in Ukraine mentioned by Nurkin.

Nato officials say they are thinking about how the rapid-reaction force would be trained for such eventualities. It is difficult at this stage to envisage just what kind of training would be relevant.

Heather Conley, a former US state department official who dealt with the former Soviet countries and is now director of the Europe programme at the Washington-based Center for Strategic and International Studies, is, like Niblett, optimistic about the summit and sees the creation of the rapid-reaction force as significant. "Nato has not had a collective defence posture since the end of the cold war," she said. "We should not focus on the 4,000 number but on the quality of the force."

One test of Nato's commitment is money, at least as far as the US is concerned. Washington pushes at every summit for increased contributions from largely reluctant European members. A report by the US Congressional Research Service, which provides information for members of Congress, said just four of the 28 members – the US, Britain, Greece and Estonia – meet the 2% of GDP target. The report, published last week, said: "Since 2001, the US share of total allied defence spending has grown from 63% to 72%."

The US is hoping, probably forlornly, that the Russia-Ukraine crisis will prompt an increase in contributions. Nato officials, in a draft proposal, have included for the first time an element calling for meeting the 2% target. But against a backdrop of defence cutbacks across Europe, US hopes are likely to remain unfulfilled.

Nato's basic problem is that it is just too big, making it difficult to get consensus among the 28 countries. Some members of Congress want Ukraine to be given fast-track membership of Nato along with other countries on the edge of Europe. But many European states are opposed.

There has been a push for the establishment of permanent Nato bases in the Baltic states but Germany and Italy have resisted, arguing it would be a violation of a 1997 Nato-Russia agreement. Instead, Nato troops are being stationed in the Baltic states on a rotational basis.

One of the biggest signs of the divergences within Europe is that France is going ahead with the supply of two Mistral helicopter carriers to Russia, in spite of calls by other Nato members not to.

Nato officials said that there was no prospect of the organisation becoming involved against Isis in Iraq and Syria any time soon. The Isis threat will be discussed at the summit but largely informally. Barack Obama may give some indication at the summit about whether the US will bomb Isis positions in Syria as well as in Iraq but that would either be a solely US operation or one in conjunction with a few close allies, not Nato.

The last Nato summit was in Chicago in 2012. It was a largely vacuous, tired affair, with the main issue on the agenda whether to accept new members. There were hundreds of unfilled seats in the media hall, with many journalists decided the trip was not worth the bother.

Against the backdrop of the Russia-Ukraine crisis and the rise of Isis, more journalists will feel it is worth turning up but Nato's post-cold war role remains in question. Nato will agree to the rapid-reaction force but that is far from a robust response to the challenges posed by Putin.

The chances are that by the end of the summit in Wales on Friday there will have been lots of "strong" signals and statements aimed at Russia, lots of new initiatives and a welter of the kind of acronyms beloved by all military organisations, but nothing that will worry Putin.