I think this comment is being downvoted unreasonably.

Regardless of the (im-)morality of weaponizing space I'm fairly certain the only binding treaty signed by the space powers addressing weapons in space was The Outer Space Treaty of '66. That only banned nuclear or other weapons of mass destruction.

As far as the definition of weapon; popular opinion isn't germain if we're discussing a legal matter, only the legal definition and how loose it might be. In the past few decades the US, Russia, and China have all shot down a satellite with missles from Earth, and generated more space junk in the process I might add. If that didn't run afoul of a treaty I don't see how this project could.