OH, to be a fly on the wall in the Kremlin looking on as Russian President Vladimir Putin reacts to the current Nato summit in the Lithuanian capital, Vilnius.

“Ukraine’s future is in Nato,” the leaders of the 31 member states said adamantly in a declaration this week. No doubt Putin is already well aware of that, but for now he will take some satisfaction in the fact that the alliance stopped short of offering Kyiv an immediate invitation.

Meanwhile, Putin’s Ukrainian counterpart President Volodymyr Zelenskyy was, as one might expect, none too pleased with the decision not to offer immediate membership.

“Unprecedented and absurd,” Zelenskyy called the lack of timetable for when his country will be formally invited to become a member of the military alliance, while also attacking the “vague conditions” for inviting Kyiv.

There’s little doubt that Zelenskyy’s fellow countrymen and women, exposed daily to continuous Russian missile and drone strikes, or those 78% of Ukrainians who have close relatives or friends who have been killed or wounded since Russia’s invasion, would side with his view on Nato’s shortcomings.

But in real terms Zelenskyy must have known that immediate membership was never a goer while his country is at war with Russia. While some might argue that Nato is already directly engaged in this war, the reality is that its position is still a far cry from what it would be were Ukraine given full membership.

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To that end, US President Joe Biden is right when he says that bringing Ukraine into the alliance while it is at war with Russia is unrealistic, as it would then draw Nato itself into the conflict in total commitment terms.

Zelenskyy’s obvious display of anger while based on a logic of sorts was also likely aimed at making some of his Nato allies feel bad enough to immediately promise a raft of other things that Ukraine so badly needs right now. Not least among these is more ammunition and weapons as its armed forces drive ahead with an offensive meant to put Russia on the backfoot, before another bitter winter and war of attrition sets in at the end of the year.

To that end, separately, the G7 group of industrialised countries continued negotiations on an overarching package to support Ukraine “as long as it takes”, which they hope to announce as soon as the Nato summit is over.

But going back to Russia’s scrutinising of the summit, if the Kremlin is sure to be pleased with no immediate Ukrainian Nato accession, then Putin will also be rubbing his hands with glee at the juggling act the alliance had to do to maintain and project unity.

This perhaps more than anything should be Ukraine’s real concern right now. For behind all the shows of Nato solidarity you can’t help sensing real differences between some of its members over the war that could grow exponentially, handing Moscow the chink in the alliance’s armour it has been looking for and so wants to exploit.

Take for example the way the US and Germany are wary of implying that Kyiv’s membership is inevitable without conditions attached. This is in marked contrast to other, mainly eastern European members, with the backing of the UK and France who have called for the word “invitation” to be included in the statement. Just before the Vilnius summit, a senior Nato source speaking on condition of anonymity was cited by the media as saying there is “a hard search on to find a mechanism that brings Ukraine closer to Nato without taking them into Nato”.

If anything has become clear these past few days in Lithuania, it’s that such a search has yet to provide such a mechanism.

Biden while in London ahead of the Nato summit might have described US relations with the UK as “rock solid,” but this was overshadowed by Washington’s recent announcement that it will send cluster munitions to Ukraine, despite the bombs being banned by 123 nations, including Britain, for their indiscriminate killing capability.

As many as 111 countries, including many Nato allies – but not the US, Russia or Ukraine – have ratified a 2008 convention to ban these especially nasty weapons whose remnants can continue to kill and maim civilians for years into the future.

Such things might seem like small beer when looking at Nato’s position on the war overall, but they point to issues that cumulatively could become a future problem for Nato solidarity. To say that Moscow meanwhile is watching such mixed messages closely would be a gross understatement.

Which brings us to the key consideration here which is that, short of Ukraine becoming a full member while the war is ongoing, Nato must at the very least unanimously agree to further boost Ukraine’s security between now and the day it joins the alliance.

To put this another way, it has to find an approach that will be strong enough to keep Russia in check while not provoking it at the same time, no easy task. Putin and his cronies meanwhile will be sniffing for any kind of softening or division.

As the Russian leader looks on at proceedings in Vilnius this week, he will be satisfied that no invitation for Ukraine to join Nato is in the offing right now.

This will allow Putin to retain his de facto veto on the process of Nato enlargement and offer reassurance of sorts that his policy of invading neighbouring countries to deter Nato membership works. Right now, it is vital more than ever that Putin does not become emboldened, and Nato stands firm.

As the war drags on, the alliance cannot afford to start bickering and this will be difficult to prevent when as things stand right now, only 11 of Nato’s 31 members meet its target of spending 2% of annual gross economic output on defence.

If Russia’s invasion of Ukraine has taught us anything this past year and more it’s the folly and danger of underestimating the threat Putin’s Russia poses. If Nato is not prepared to give Ukraine membership yet, then at the very least it must give Kyiv the military tools and support to win on the battlefield until it is prepared to bring it into the alliances’ fold.

Any alternative doesn’t bear thinking about.