Foreign Ministry spokeswoman Maria Zakharova said US Department of Defence reports about deploying low-yield submarine-launched ballistic missile warheads had not gone unnoticed by Moscow.
She condemned the US move as “dangerous” and said the announcement carried with it an “element of destabilisation” and a “purposeful blurring between non-strategic and strategic weapons.”
Ms Zakharva warned it would lead to a “lower threshold and an increase in the threat of nuclear conflict”.
She said: “I would like to stress that any attack using a US submarine-launched ballistic missile, regardless of its characteristics, will be perceived as a nuclear-weapon attack.
“Those who want to speculate about the flexibility of the American nuclear potential should understand that according to the Russian military doctrine, such actions will be considered a foundation for retaliatory use of nuclear weapons by Russia.”
The US Pentagon announced the US Navy had deployed the W76-2 low-yield submarine-launched ballistic missile (SLBM) warhead to deter Russia’s and China’s nuclear threat.
Tensions are running high with US officials fearing Beijing and Moscow are trying to take advantage of the global coronavirus pandemic to increase their influence using military means.
Russia has flown two nuclear-capable Tu-160 strategic bombers over the neutral waters of the Baltic Sea in a move that prompted Finland, Denmark, Poland and Sweden to scramble jets to escort them.
The Russian Defence Ministry said the flight was routine in nature and strictly adhered to international airspace regulations.
Russia carries out similar training flights over the Arctic, Atlantic and Pacific oceans, as well as over the Black and Baltic Seas on a regular basis, a policy some NATO members regard as unhelpful sabre-rattling.
A Defence Ministry spokesman said the two Tupolev T-160 aircraft, which can carry up to 12 short-range nuclear missiles, were in the air for eight hours.
He said: “At specific stages of the route, the aircraft were escorted by the Finnish Air Force’s F-18s, Royal Danish and Polish Air Force F-16s, as well as by the Swedish Air Force’s Saab JAS 39 Gripen fighter jets.”
Russia made a similar statement on yesterday, saying two Tupolev Tu-22M3 strategic bombers had flown a routine four-hour flight over the neutral waters of the Barents and Norwegian seas, prompting Norway to scramble its jets to escort them.
It also confirmed advanced jets belonging to its Baltic Fleet had rehearsed striking naval targets in the Baltic Sea.