With Russia expected to soon carry out large-scale drills of its nuclear forces as President Vladimir Putin threatens to use them, the United States and its allies will be challenged to ensure they can spot the difference between exercises and the real thing.

Russia typically holds major annual nuclear exercises around this time of year, and US and Western officials expect them perhaps in just days. They will likely include the test launch of ballistic missiles, US officials say.

But with Putin having openly threatened to use nuclear weapons to defend Russia in its unraveling invasion of Ukraine, some Western officials are worried Moscow could deliberately try to muddy the waters about its intentions.

"This is why you don't want to have extraordinarily overheated rhetoric at the same time you're going to do a nuclear exercise," a Western official told Reuters, speaking on condition of anonymity.

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"Because then we do have an additional challenge to really be sure that the actions that we see, the things that are occurring, are actually an exercise and not something else."

Still, the official expressed "high confidence" in the West's ability to make this distinction.

NATO Secretary-General Jens Stoltenberg assured a news conference in Brussels that the alliance would monitor Russia's annual nuclear drills very closely, as it has for decades.

At the White House, National Security Council spokesperson John Kirby said Russia's so-called "Grom" drills would involve large scale maneuvers of its strategic nuclear forces, including live missile launches. He described them as "routine."

"While Russia probably believes this exercise will help it project power, particularly in light of recent events, we know that Russian nuclear units train extensively at this time of year," Kirby said, adding the United States would "monitor that accordingly."

A US defense official, speaking on condition of anonymity, said the Russian drills were expected to be carried out about the same time as NATO's own annual nuclear preparedness exercise, which is dubbed "Steadfast Noon" and will begin next week.

"We believe that Russian nuclear rhetoric and its decision to proceed with this exercise while at war with Ukraine is irresponsible," the official told Reuters.

"Brandishing nuclear weapons to coerce the United States and its allies is irresponsible."

The Russian Defense Ministry did not immediately respond to an emailed request for comment.

Officials have so far said Putin has not yet taken steps to suggest he's preparing to launch a nuclear strike, but Moscow's nuclear rhetoric has intensified following a successful counter-offensive by Ukraine's military over the past month.

In recent weeks Putin has proclaimed the annexation of Ukrainian territories and threatened to defend Russian land with nuclear weapons. A senior NATO official said on Wednesday any use of nuclear weapons by Russia might trigger a "physical response" from the alliance.

US Defense Secretary Lloyd Austin said on Thursday after a meeting of NATO's nuclear planning group in Brussels that he had not seen any "indications and warnings" that would cause a change to the US nuclear posture.

Russia last exercised its in February, shortly before its invasion of Ukraine, in a move officials at the time believed was meant to discourage the West from supporting Kyiv.

The Western official expected drills meant to test "the Kremlin's ability to provide control over the forces and to issue direction, and of the forces themselves to respond to that direction."

The official anticipated that Russia would publicize aspects of the drills, and use them to drive home Moscow's threats.

"We should expect that there will be nuclear rhetoric during the exercise, so that they can take advantage, strategic communications advantage, of the exercise itself," the Western official said.

NATO's own annual nuclear exercise was planned before Russia's invasion of Ukraine, US officials said, adding it has been held regularly at around the same time of the year for over a decade. The bulk of the drills will take place more than 1,000 kilometers (625 miles) from Russia, the US defense official said.

Fourteen NATO nations are expected to be involved in the alliance's drills, which include fighter jets capable of carrying nuclear warheads -- but does not involve live bombs, the US officials said, adding US military B-52 bombers will participate.

"While we will continue routine activities to sustain our (nuclear) deterrent, there will be no special messaging around our exercises," the US defense official said.

"We think nuclear saber rattling is reckless and irresponsible. Russia may choose to play that game – but we won't."