The US is preparing to tell dozens of countries they must pick sides in the artificial intelligence race with China, warning they will be excluded from a US-led AI coalition if they also sign up for Beijing's competing framework, according to a US official and an internal draft reviewed by Reuters.Washington last year launched the Pax Silica initiative aimed at securing supply chains for AI models, semiconductors and critical minerals, amid a fierce technology rivalry with Beijing.About two dozen countries have joined, including Kazakhstan, a key potential source of critical minerals that has also joined China's coalition, as well as…