Defense Opinion – Once again, the undersea domain is growing contested, as it was during the Cold War. Unmanned underwater vehicles (UUVs) promise to enhance the combat reach and responsiveness of existing U.S. nuclear submarines. They remain, however, a complementary capability, and not a substitute for the irreplaceable advantages of manned nuclear submarines. The U.S. Navy should pursue the concept of teaming manned units — like attack submarines — with unmanned units as the best method to maximize combat potential.