I am primarily concerned with how the government establishes jurisdiction in this case. Assange is a foreigner, and every single one of his actions were done i

I am primarily concerned with how the government establishes jurisdiction in this case. Assange is a foreigner, and every single one of his actions were done in a foreign country. At what point does the United States government gain the authority to apply United States legal code to his actions? There might be an obvious answer to this, but I honestly don't understand it.