London: Is Nato suffering the 70-year itch? Repeated declarations of solidarity from the alliance's leaders this week hardly masked the squabbling between Presidents Trump, Macron and Erdogan or the carping stage whispers from Justin Trudeau. Nor did the summit do much to contradict Mr Macron's assertion that Nato's lack of clear common strategies for the future indicated its "brain death".
Secretary-General Jens Stoltenberg made a brave effort to talk up Nato's new force structures and members' commitments to an alphabet soup of reforms. But bureaucratic tinkering cannot mask the risk of the alliance falling into a "permanent vegetative state" unless it grasps the need for bigger thinking. What is the point of Nato decades after the collapse of the USSR? Everyone seems to have a different answer. Does the solidarity still exist for its members to come to each other's aid? It's doubtful.
Let's not downplay matters. The French President's call "to reassess the reality of what Nato is" is evidence of an alliance in crisis. Mr Macron diagnosed Mr Trump's lukewarm enthusiasm for Nato as the sickness, and prescribed the creation of some sort of EU army as the medicine. For Mr Trump, the big problem is that European allies have relied on US troops while complacently offering little themselves. He has been happy to take credit for an increase in Nato contributions, but his continued support for the alliance can hardly be taken for granted.
Then there is the problem of Turkey, a Nato member but nevertheless accused by Mr Macron during the summit of having colluded with Islamic State jihadists in Syria. Under President Erdogan, Turkey today has turned against the Western values that Nato ultimately defends.
All told, this is an alliance that is fraying at the edges - unable to pull in the same direction and unwilling to get to grips with why.
Overhanging all this is a global threat environment that suggests now is hardly the time to take a lax attitude to defence. There is no question that the democratic world faces unprecedented threats.
The rise of China and its rapidly growing co-ordination with Russia is dramatic. In effect, the two are creating a giant Eurasian power bloc. Even when Stalin and Mao were allies, Moscow and Beijing lacked the economic and technological resources now available to Vladimir Putin and Xi Jinping. Russian missile technology plus Chinese money makes for a superpower comparable to the US.
While it's understandable for a defensive alliance to prioritise warding off immediate threats, the failure this week to move beyond relatively ephemeral discussions on issues such as space warfare to grapple with broader fundamentals suggests that Mr Macron's plea for a wider discussion about Nato's underlying issues has fallen on deaf ears.
Above all is the question of whether a regional alliance even makes sense in a globalising world. There is a strong argument that leaders would be better off supporting a worldwide alliance built on shared values, rather than geographical proximity.
For what it's worth, my view is that if Nato were reoriented around the defence of values as well as territory it would secure a greater element of unity. Current members have far more in common with the likes of Australia, New Zealand and Israel than they do with Turkey. Expelling members who flout democratic principles while welcoming those who hold these values dear would give the alliance the chance to punish Mr Erdogan. Meanwhile, using the promise of future membership as leverage would encourage more of the world's despots to adopt democratic and human rights reforms.
Inviting new members from other areas of the globe - in particular from the Pacific region - would also help assuage some of Mr Trump's concerns about the rise of China. Such a reorganisation would not be straightforward, but it would create an alliance that had some sense of purpose and togetherness - the malaise currently at the heart of modern Nato. At the very least, this is the sort of discussion that an alliance desperate to prove it is not "brain dead" ought to have been having.
The Telegraph, London