The warheads, according to Russian state news are nuclear warheads that would be installed on their missiles as opposed to the conventional ballistic missile warheads that are presently being employed in Ukraine.
"To protect the territorial integrity of our country, ballistic and cruise missiles with special warheads will be used... This will be the proverbial Apocalypse." – states the former Russian President and current chairman of the country’s Security Council Dmitry Medvedev
The remarks made by Medvedev coincide with a growing discourse among NATO allies over readiness for a prospective conflict with Russia.
Putin made remarks prior to his invasion of Ukraine that suggest the conflict may have less to do with Ukraine and more to do with Russia's anxiety over NATO's growth into Eastern Europe.
Russia claims that it has no plans to escalate the current conflict, but it also stated the same that it had no plans to invade Ukraine when it gathered artillery and military hardware on the Ukrainian border, asserting that this was done only for military exercises prior to the invasion.
"The Alliance will continue to respond to Russian threats and actions in a united and responsible way." – states NATO
Source: The Standeford Journal