Former navy submarine officer here. So SIGINT is absolutely a capability of US submarines, but isn't necessarily a primary purpose. But there are absolutely t

Former navy submarine officer here. So SIGINT is absolutely a capability of US submarines, but isn't necessarily a primary purpose. But there are absolutely times and places where the ideal source of intelligence for the US government is a submarine offshore of country X with very small masts sticking out of the water gathering SIGINT. Satellites don't/can't catch everything.