There was a time our country was VERY good at killing the enemy’s diesel subs. I can’t imagine we have forgotten everything.
Technology works for you and against you. In this day and age of technology transfer and theft, even third world rag head cesspools can conjure up effective weapon systems.
Diesel-electric subs got a lot better and a *lot* quieter. The latest ones from multiple countries around the world can stay submerged underwater for weeks. The way we found most enemy diesel subs through the 70s was by hearing them come up to snorkel depth and start their diesels to recharge; modern boats have air-independent propulsion and charging systems; some use noiseless fuel cells as generators.
*Allied* modern diesel, which should these days really be called non-nuclear, boats have routinely penetrated US carrier battle groups that knew they were supposed to be there - and gotten point blank shoots on carriers. Non-nuclear subs got a lot better: https://nationalinterest.org/blog/the-buzz/swedens-super-stealth-submarines-are-so-lethal-they-sank-us-18383