It is not against the Outer Space Treaty to weaponize space. We have already tested ASAT weapons as have the Chinese and Russians, this has been in the news over the past several decades. The OST only bans military bases on the moon and other planets and moons, and deploying nuclear weapons in space. It does not ban any other sort of military activity there. Secondly the Space Liability Convention actually puts a legal burden on the US to exercise lawful jurisdiction over all spacecraft launched from US territory or operated by US agencies or companies. How can you exercise a legal jurisdiction if you cannot place policemen there to enforce that jurisdiction?