@randahl From a European perspective the US is the biggest threat to world peace right now, let alone threat to the US. Russia 2nd. China doesn't really feature, it's only economic.

NATO exists to stop Russia, China or anyone else invading a NATO country (e.g. Greenland). Not only would the US be forced to respond if anyone attacked Greenland the whole of NATO would. But if a NATO member does it, it just destroys NATO and Russia and China would break out the champagne, and Trump would try and make money from the rare minerals as that's the real reason he is doing it.