Moscow has been employing nuclear warnings and threats since the start of its invasion of Ukraine in February, with its rhetoric being described as “reckless” by US officials.

The US has said it expects Russia to carry out test launches of missiles during its annual “Grom” exercises of its strategic nuclear forces, noting in the past it has fired inter-continental ballistic missiles.

US officials say Russia is obliged under the New START Treaty to provide advance notification of such missile launches.

“The US was notified, and, as we’ve highlighted before, this is a routine annual exercise by Russia,” spokesman Air Force Brig. Gen. Patrick Ryder announced at a news briefing.

Such drills represent a potential challenge to the US and its allies, as Russian President Vladimir Putin has previously threatened to use nuclear weapons to defend Russia amid its ongoing aggression against Ukraine.

Questions have also emerged as to whether Moscow may unleash a lower-yield “tactical” nuclear weapon on Ukrainian soil.

Russia on Tuesday also flagged allegations to the UN Security Council that Ukraine is preparing to use a “dirty bomb” on its own territory, an assertion flatly dismissed by Western and Ukrainian officials as misinformation and a pretext for further conflict escalation.

Western officials have expressed confidence in their ability to discern the difference between a Russian drill and any move by Putin to act on his nuclear threats.

At the US State Department, spokesperson Ned Price stressed the importance of compliance with such notification requirements.

“While Russia engages in unprovoked aggression and reckless nuclear rhetoric, these notification measures do ensure we’re not taken by surprise and reduce the risks of misperception,” Price said.