In a briefing held on 29 April, Maria Zakharova,Foreign Ministry spokeswoman, said that 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.