In the four months since the leaders of the two global superpowers last met, Xi Jinping has overseen a surge in China's trade with the world while Donald Trump has struggled with falling approval ratings at home.

That shift in fortunes has tempered expectations for their summit in Washington this week, analysts say, with Xi in no rush to make concessions and Trump constrained by ‌a costly war with Iran that has hurt both his popularity and Americans' wallets.

For years, the race to build ever-more powerful artificial intelligence followed a well-worn Silicon Valley principle: move fast and break things.

But in a series of cascading events over a 10-day stretch, the largest AI labs found themselves reeling as their own creations threatened to break humanity itself.