A senior Pentagon official warned on Friday that Russia is “playing with fire” when it suggested that it could use nuclear weapons to settle international disputes, and accused Moscow of trying to intimidate NATO through such threats.

"Anyone who thinks they can control escalation through the use of nuclear weapons is literally playing with fire," U.S. Deputy Secretary of Defense Robert Work told a House Armed Services subcommittee, the Independent reported. "Escalation is escalation, and nuclear use would be the ultimate escalation."

While Moscow has not issued any direct nuclear threats, Russian officials have made several references to their nuclear arsenal and announced the construction of 40 new nuclear-capable intercontinental ballistic missiles, a move that Washington has denounced as “saber-rattling.”

Leaked documents from an April meeting between U.S. and Russian officials revealed that Russian officials discussed a “spectrum of responses from nuclear to non-military” if NATO went ahead with its plans to enhance its military presence in the Baltic States, the Independent reported.

Russia has also threatened several Baltic nations that they would be considered potential nuclear targets if they joined NATO’s missile defense program. In March, the Russian ambassador to Denmark warned that “Danish warships would be targets for Russia’s nuclear weapons,” if the country joined the military alliance.

The Baltic states have seen a growing number of incursions and flyovers from Russian bombers and ships. Russian planes were intercepted over the Baltic Sea 10 times last week.

Russian President Vladimir Putin, in a March documentary on the annexation of Crimea, said he was prepared to place Russia’s nuclear forces on alert

Moscow’s recent military overtures were also condemned by the U.S. "Senior Russian officials continue to make irresponsible statements regarding its nuclear forces, and we assess that they are doing it to intimidate our allies and us," Work said. "These have failed. If anything, they have really strengthened the NATO alliance solidarity."

Friday's statement comes shortly after NATO announced a major escalation of its own military presence in eastern Europe, which would see thousands of vehicles and troops deployed across Estonia, Lithuania, Latvia, Bulgaria, Romania and Poland.