I cannot imagine how Macron could possibly have thrown a bigger stink-bomb towards NATO ahead of the London summit of leaders in December. Extraordinary words, and extraordinary timing.
'NATO, Mr Macron says, “only works if the guarantor of last resort functions as such. I’d argue that we should reassess the reality of what NATO is in the light of the commitment of the United States.”' economist.com/europe/2019/11…
'Mr Macron’s underlying message is that Europe needs to start thinking and acting not only as an economic grouping, whose chief project is market expansion, but as a strategic power. That should start with regaining “military sovereignty” & re-opening a dialogue with Russia ...'
Macron: '“You have no co-ordination whatsoever of strategic decision-making between the United States and its NATO allies. None. You have an unco-ordinated aggressive action by another NATO ally, Turkey, in an area where our interests are at stake.”' economist.com/briefing/2019/… 
The fundamental issue with Macron's death-knell for NATO is that none of the stuff he cites (EII, PESCO, EDF; see below) comes even remotely close to filling a US-sized hole, so hard to see what is gained by making such an explosive comment publicly, even if the analysis is sound
Also notable is that Macron's sceptical question -- “what will Article Five mean tomorrow?” -- seems to presuppose that Article Five's future depends on American intentions alone. That is wrong. There are collective security doubts (principally, weak public will) elsewhere.
The full transcript of the interview with Macron is here: economist.com/europe/2019/11… "J’ajoute que nous devrons à un moment faire le bilan de l’OTAN. Ce qu’on est en train de vivre, c’est pour moi la mort cérébrale de l’OTAN. Il faut être lucide."
In July I wrote a piece for our annual supplement, 'The World If', looking at what might happen if America did leave NATO, and how Europeans might respond. More of a thought experiment than a forecast: economist.com/the-world-if/2…
Also worth reading this very good @IISS_org analysis from back in May. "European NATO members would have to invest between US$288bn and US$357bn to fill the capability gaps ... to prevail in a limited regional war in Europe against a peer adversary" iiss.org/blogs/research…
