Russia's Nuclear Weapons: Doctrine, Forces, and Modernization [Updated January 2, 2020] [open pdf - 2MB]
From the Introduction: "This report [...] is divided into five sections. The first section describes Russia's nuclear strategy and focuses on ways in which that strategy differs from that of the Soviet Union. The second section provides a historical overview of the Soviet Union's nuclear force structure. The third section details Russia's current force structure, including its long-range intercontinental ballistic missiles (ICBM), submarine-launched ballistic missiles (SLBM), and heavy bombers and shorter-range nonstrategic nuclear weapons. This section also highlights key elements of relevant infrastructure, including early warning, command and control, production, testing, and warhead storage. It also describes the key modernization programs that Russia is pursuing to maintain and, in some cases, expand its nuclear arsenal. The fourth section focuses on how arms control has affected the size and structure of Russia's nuclear forces. The fifth section discusses several potential issues for Congress."
CRS Report for Congress, R45861
Congressional Research Service: https://crsreports.congress.gov/