The Russians and the NORKs just agreed to use any means available to each other’s mutual defense. That means nukes and Russia is the world leader in tactical nukes they never got rid of them like the USA did. They have slews of battlefield munitions from 10kt artillery shells to hypersonic zircons with 100+kt boosted. It’s always been Soviet and Russian policy to use tactical nukes if they are losing ground. They don’t use strategic level PAL links their individual battlefield commanders have special weapons release codes and the keys to use them. This was first learned in the Cuban crisis and remains the same today.
“The Russians and the NORKs just agreed to use any means available to each other’s mutual defense. That means nukes”
It means “nukes” if Russia and the NORKs feel “nukes” are needed.
However, they both know the U.S, would respond massively “in kind” should Russia or the NORKs do that.
By the way, we have battle field “nukes” to be deployed in the defense of S.K. if the occasion demanded it. They have been moved to safety in Okinawa (they used to be only about 20 miles south of Seoul) so their stores are not a target in S.K. Their storage and well-trained operations (what their unit trains for) would move them to S.K. soil on request where ground operations would be ready to move them where needed.