Why diesel submarines remain a difficult anti-submarine target

During a Cold War conflict, nuclear boats could range widely while diesel boats massed around Soviet ballistic-missile submarine bastions and moved into North Atlantic defensive lines. A diesel submarine on batteries could become an acoustic void. A nuclear boat might be extremely quiet, but its reactor still had to run. Conventional submarines were easier to kill in some respects, yet their numbers and different acoustic behaviour made them dangerous. US Navy exercises with small allied diesel boats illustrate the training problem: crews accustomed to hunting nuclear submarines also needed experience against quieter conventional targets. Nuclear submarines delivered high-end capability at a cost that limited their numbers. Anti-submarine methods could not be treated as interchangeable across the two types.