Yes, consider the following scenario, Using some political pretence, China invade Taiwan in a blitzkrieg which is over in a few days. All US communications and GPS are wiped out before the attack begins. Total chaos. Allies are blind. Any US forces in the vicinity trying to prevent the attack are obliterated. Next days China issue the following decree, Taiwan has joined the motherland and all regrettable attacks on US forces have stopped and a ceasefire is in effect. Any attack on China and Taiwan will be meet with nuclear forces. What will US and Nato do? What did they do when Russia elbowed itself into the Syrian conflict? That's right, nothing.
The point is, any serious attack done by China will be over before US an allies can stop it or reply properly, unless there is a believable rapid response force on location.