Why have the americans and British exited the international submarine market. Why don't they make diesel subs anymore?
The USN hasn't bought a diesel submarine since the70s. And the last conventional sub was decommissioned in the early 90s.
Diesel worked for the Pentagon's War Plans to deter the Soviets, they'll be launched from forward bases in the Pacific, England, Cuba, Australia, combined with the Allied subs, would take out Communist Naval forces securing and keeping open Naval routes. Back then you needed not only proximity to well traveled routes but the quantity to slug it out against the enemy, now a Destroyer captain can launch Harpoons to take out a sub tens of miles away.
Diesel Subs are meant to sneak into the Enemy's coastal waters loiter there for a few weeks, Nuclear Subs with the advancement of ICBMs can wretch havoc on Beijing from the waters of Chile.
The Soviets fell, the Pentagon couldnt find a bogeyman to maintain it's "500 ship Navy". Diesel works well in wolfpacks. The USN is dispersed through out the world. Odds are that if a war does break out with say N. Korea the USN isn't going to have enough ships to confront the initial wave Kim Jung will throw, but the technical gap itself will preserve the force.
The US is the world's undisputed policeman. There only needs to be enough deterrent to deter aggression than the quantity of ships that can be thrown.
At the end of the day it's dollars and cents. Sure the Soviets bankrupted themselves trying to match President Ronald Reagan's military expansion, but the US itself was on the fence. While the USN is planning on decreasing it's Submarine Force, Japan is expanding there's so is Australia, Germany, and perhaps Britain?
Sure the Swedish Gotland caused a panic to the US Naval Admirals, but when the US decide to rent the sub to formulate, test, and train it's crews to counter the most advanced diesel sub to date, it had to be shipped to the Pacific on a barge!!!
SSKs are impractical for the USN. You'll need forward bases, security for those bases in the form of a marine force, an airbase, security for that airbase, jets for that airbase, etc etc etc.
Like earlier it comes to money. Why not let the US focus on the big guns, ie Nuclear Subs, and let Japan/ Australia/ UK/ France focus on the SSKs. Because in the end, those will be the forwards bases and in close proximity to any conflict that will rise.
This is all written without analysis of the US Military Industrial Complex. There's allot more money to be made with a few Nuclear Subs than ~7 Diesel ones.