Russia’s defense ministry on Wednesday said it would mobilize more than 4,000 soldiers, 400 technical units and major air support for a large-scale nuclear exercise, just days after Russian President Vladimir Putin made a veiled threat about Russia’s nuclear arsenal amid the ongoing crisis in Ukraine.

The exercise will be conducted in Altai in south-central Russia, according to The Moscow Times, and comes one day before the beginning of a NATO summit in Wales. It will specifically include Supersonic MiG-31 fighter-interceptors and Su-24MR reconnaissance planes, along with Spetsnaz special forces units role-playing as enemy forces. (RELATED: NATO Releases Satellite Photos Proving Russia Is Lying About Invading Ukraine)

Strategic rocket forces Major Dmitry Andreyev said the simulation will have units “conducting combat missions in conditions of active radio-electronic jamming and intensive enemy actions in areas of troop deployment” to counter “irregular units” and “high-precision weapons,” according to the report.

Andreyev also said the scale of air power included would be unprecedented for such an exercise.

“I want to remind you that Russia is one of the most powerful nuclear nations,” Putin said Friday at a youth forum, news.com.au reports. “This is a reality, not just words.”

Ukrainian Defense Minister Valeriy Geletey wrote on Facebook earlier this week that a “great war arrived at our doorstep, the likes of which Europe has not seen since World War II,” adding it could result in “tens of thousands of deaths.”

In a conference call with reporters ahead of this week’s NATO summit, White House Senior Director for European Affairs Charles Kupchan warned Russia against interference in other former Soviet states.

“Russia, don’t even think about messing around in Estonia or in any of the Baltic areas in the same way that you have been messing around in Ukraine,” Kupchan said, according to al-Jazeera America.

Despite the warning, NATO is not expected to intervene in Ukraine, which is not a member nation.

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