"I think the rift is one that happens periodically between the UK and US - without minimizing the significance, there have been tensions on trade issues for some years now (including the tariffs imposed by the Trump administration on the UK). How serious it becomes is questionable," says Professor Robert Singh, specialist in contemporary US politics at the University of London's Birkbeck College.
"It's possible that [the NIP amendment] could then inflame the trade issue further," says Singh. "[I]t will worsen the Johnson government's record, at a time when the cost of living crisis, inflation, and many other problems are piling up. It's probably, on balance, yet another own goal by Johnson - an unnecessary diplomatic row that was avoidable."
UK-US Spat Can be Fixed Quicker Than That Between UK and EU
"Johnson and Biden are both career politicians and will probably behave pragmatically," says Fuller. "Even were they to exaggerate their differences in the press to play to their respective electorate, this would be unlikely to affect their highly connected working relationship greatly."
"Britain also obviously lost faith in the EU and its regulatory regime, and clearly wants to go its own way to the extent that it can," the author says. "This is thus an example of increasing global fragmentation."