Russia is in the late stages of a multi-decade-long modernization program to replace all of its Soviet-era nuclear-capable systems with newer versions. However, this program is facing significant challenges that will further delay the entry into force of these newer systems. In this issue of the Nuclear Notebook, we estimate that Russia now possesses aproximately 4,400 nuclear warheads for its strategic and non-strategic nuclear forces—a slight increase from the previous year. The significant increase in non-strategic nuclear weapons that the Pentagon predicted five years ago has so far not materialized. A nuclear weapons storage site in Belarus appears to be nearing completion.