Diesel submarines are cheap, defensible, and punch above their weight. Here's What You Need to Remember: The seemingly mundane tradeoff between ship types and budget lines carries fateful import for U.S. foreign policy. For the past five years or so these pixels have been arguing—nay, clamoring—for the U.S. Navy to build or buy a contingent of diesel attack submarines (SSKs) to fill out its undersea inventory. If anything the logic for going conventional is more compelling now than ever. It offers a way to add new hulls with dispatch, at a manageable cost, and without imposing extra burdens on the few shipbuilders that specialize in naval nuclear propulsion. Best of all, a diesel contingent is an ideal implement for executing U.S. strategy in what the Pentagon terms its “priority theater,” bar none: the Indo-Pacific.