The head of the Russian space agency Roscosmos has announced his country's deployment of a new type of intercontinental ballistic missile.
Russian media quoted Yuri Borisov as saying on Friday that the missile system known as Sarmat has been put into "combat duty."
President Vladimir Putin has spoken about the missile for a year, previously saying that it would be ready for use "in the near future."
Sarmat is capable of carrying 10 or more nuclear warheads. Putin has said that it can overcome "all modern means of anti-missile defenses." He claims it will help to protect Russia from what he calls "external threats."
Leaders in Moscow have been ramping up their nuclear rhetoric as their losses mount on the battlefield.
Ukrainian commanders say, over the past week, that they have succeeded in liberating the village of Robotyne in the southeast.
Deputy Defence Minister Hanna Maliar said Friday that even in conditions where the enemy has more fighters and more weapons, their troops are gradually "moving forward."
Despite the losses, Russian troops have taken time to meet with their allies for training drills. More than 2,500 have gathered under the alliance known as the Collective Security Treaty Organization.
They have expanded the exercises to include responses to a nuclear accident. The drills include personnel from Belarus, Kazakhstan, Kyrgyzstan and Tajikistan.