This is the PRC mantra, and the US isn't buying it.
The reverse can be said as well, that PRC isn't buying the idea that US enforcement of freedom of navigation is unrelated to its military surveillance of strategically important military facilities.
Let's put out a hypothetical question here -- do we think China would be pressing its claims or seeking to enforce them in such a great urgency if there was not such consistent US surveillance aircraft and ships near China's important facilities?
Let me pre empt a response, by first saying that yes, China has also on occasion sailed and flown similar surveillance flights, and it is within the rights of the US to use whatever legal means to achieve its aims -- even if this includes forward positioning and conducting intensive and comprehensive reconnaissance of a potential foe's strategic military facilities such as nuclear submarine bases.
However China also has the right to use means to try and pre empt it in whatever means within the flexible bounds of international law.
What I do not find reasonable however, is when one side tries to use freedom of navigation as a lead in for conducting these kind of surveillance actions. If the US straight up said "we desire to have overwhemling ISR for our forward based air and naval assets against our strategic competitors" -- that I can accept. I don't even need the US govt to acknowledge it, but it would be nice if we on an online forum that talks candidly about military matters can straight up describe each other's intentions.
Closing down one of the world's biggest maritime trade route is a very major concern to not only China's immediate neighbors, but with all trading nations around the world.
Of course, but what makes anyone think China would seek to close down maritime trade in that area when China is so dependent on maritime trade itself?
Let's ditch the holier than thou attitude -- this entire issue rests upon power and mistrust.
Neither side trusts each other to have power in this waterway where trade flows through.
China doesn't like the US having control over its SLOCs and the US wouldn't like China to have control over SLOCs where some of its trade and much of the world's trade goes through, because both sides mistrusts each other's potential intentions in different contingencies.
Relating it back to the first part of my reply -- the US would also like to have a highly capable forward deployed presence near China's borders along with comprehensive ISR about China's military and strategic capabilities, meaning it requires relatively complete control of waters near China including the SCS.
China would obviously prefer it if the US wasn't so close to its borders and that it could have safe basins for its land bases and navy ports and nuclear submarine docks which were not so close to the effective reach of potential US carriers, destroyers, striker fighters and submarines.
I'm not going to say if either side is right or wrong, I will only say that both sides have a right to their requirements but it would be nice if we could all candidly speak about it instead of beating around the bush.