At times, Kevin Roose writes, it feels like he is watching policymakers on horseback trying to install seatbelts on a passing Lamborghini.

But many attendees at a summit in Paris worry that the risks of A.I. will be overlooked as the continent rushes to keep up with the United States and China.

In Paris, the two officials acknowledged potential strains on alliances with the return of Donald J. Trump to power, but said their countries would try to maintain strong ties.

With 211 million followers on social media, the multibillionaire seems intent on using his global platform to rattle British politics.