Such first strike capabilities are the holy grail of great power strategic warfare. Again, it's very similar to the capabilities of nuclear submarines, but far more potent. It's because of things like this that the Cold War continued to stay cold, the knowledge that no matter what happened, both the Kremlin and the White House will be obliterated within the first hours of a nuclear war, and that there were no effective countermeasures.
And as the military competition between China and the US heat up, space will inevitably become a new battlefield. Right now it's already clear that China intends to target American GPS satelites, both by laser jamming and by outright destruction.