First,This Chinese claim is for China's "Domestic Consumption"..reality has nothing to do with this..
Second,As reports suggest,its PLAN who is under "Near Blockade"..They can't make a move without Japanese-Australia-USN-South Korea and India hearing about it..
I'm posting a pic,which is quite old Undersea Defense Line...
View attachment 246089
just look at it.It is no wonder why one year back,their submarines got detected 22 times in IOR only.
To make a blockade,you need whole lot of things..Control on Airspace and it is needed to have support of Surface Fleet.ASW is a big threat for isolated submarines as it becomes an easy target.
and another thing...
India is not "Philippines"(Hell,I doubt they can make a blockade against Philippines with 10 subs)..Its having a vast coast.just one food for thought..Germany having massive amount of subs in Atlantic couldn't make a successful blockade against small nation like Britain..and here we're,talking about a blockade against a country which is thousands of km away,have a very powerful navy and potent ASW capabilities and situated right next to world's busiest sea lane.
and another thing..I wonder which submarine they'll want to use..Because most of their SSK's willn't have 2 weeks of "Station Time".and as fact suggests,to continuously deploy 1 submarine in station all the time,one needs 3 submarines(1 in station,1 which is going to relieve it and one is returning from station),which means to perform it,it'll need some 30 subs(if SSK).Now if we think that submarine availability rate of PLAN is around 40%(I doubt),then PLAN needs around 80 SSKs..Another problem will be,void of any "Support Base",how well this sub fleet will continue is very doubtful.
of course,one doesn't need to understand all these prospects when it comes about "Chinese Claim".when you see it,simply treat it as trash..