Report to Congress on Navy SSN(X) Next-Generation Attack Submarine May 11, 2021 9:21 AM The following is the May 10, 2021 Congressional Research Service In Focus report, Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress. From the report Introduction and Issue for Congress The Navy wants to begin procuring a new class of nuclear-powered attack submarine (SSN), called the Next-Generation Attack Submarine or SSN(X), in FY2031. The SSN(X) would be the successor to the Virginia-class SSN design, which the Navy has been procuring since FY1998. Congress approved $1 million in initial research and development funding for the SSN(X) program in FY2021.