The US offer to provide Taiwan with non-nuclear (diesel-electric) submarines raises some interesting questions. First, none of the usual suppliers of non-nuclear subs is inclined to offend China by supplying subs to Taiwan, or technology to the US so American yards can build the subs. But there are other forces, mainly the US Navy, that work against non-nuclear subs being built in the US. The official navy reason for resisting building non-nuclear subs in the US is that there is limited space in US ship yards for building subs and we need all the available resources for building nuclear subs. The unofficial reason is that there is fear that when a sub building firm has no contracts for nuclear subs, it will lobby for a contract to build a diesel submarine that the navy would be forced to put into service. While most naval officers want nothing to do with non-nuclear subs, the navy actually needs some diesel-electric subs so that American ships and subs can practice dealing with hostile diesel subs. Non-nuclear subs are a major threat to American naval power and while there are occasional training exercises with allies who operate non-nuclear subs, the training is much better if you have your own diesel-electric subs. Modern non-nuclear subs carry equally modern wire guided torpedoes and anti-ship missiles. Quieter than most nuclear subs, they are capable of getting close enough to a carrier task force to unleash half a dozen torpedoes and missiles at close range. Without a lot of practice against such subs, American ships could be very vulnerable.