how many subs do you think we need...
just one.
but i am sure there are plenty there... not being seen.
Remember, a Chinese Diesel Electric Sub showed up in the middle of one of our Carrier Groups without being detected back in 2007.
https://www.dailymail.co.uk/news/article-492804/The-uninvited-guest-Chinese-sub-pops-middle-U-S-Navy-exercise-leaving-military-chiefs-red-faced.html