"China already has operational ground-based missiles that can hit satellites in low-Earth orbit and “probably intends to pursue additional ASAT weapons capable of destroying satellites up to geosynchronous Earth orbit,” says the Defense Department’s annual report to Congress on China’s military capabilities."

The problem with defending a satellite is the missile really only needs to get kinda close. And yeah, relativistic speeds and distances in space are huge, but I would find it hard to believe we could defend our satellites in any meaningful way against a nation-state level threat.