Islamic nations would obviously rush to defend Pakistan.
Europe would have to take sides at some point and would certainly not offend the Islamic world.
Australia is rapidly becoming an economic colony of China and is moving quickly away from the US, so it will probably have to take sides with whatever nation China supports.
Brazil is turning into a major power. How would it respond? The nations of Africa are enjoying large investments from China. They would likely side with China - except in those nations with large Muslim populations.