The Pentagon is beefing up NATO's nuclear stockpiles, replacing old warheads with the new B61-12 thermonuclear bombs

FUCK THESE ASSHOLES

Probably because those particular nuclear bombs are gravity bombs dropped by an aircraft. They are not on missiles and can't possibly be fired by mistake.

And the B61-12. It's actually the oldest bomb in the stockpile, built in the 1960s. They're just putting new tail-fins on them to make them more accurate, allowing them to reduce the warhead yield.

This damn story just keeps getting messed up.

They are old war heads, they are adding modern guidance systems to them. Making them tactical nukes with precision aiming and allowing them to be dropped from higher altitudes and from faster aircraft's and actually gaining accuracy over the old method despite the higher altitude and faster speeds they will be deployed under. The old method used an attached parachute for deployment and "aiming"

They are making a larger version of our tactical modern nukes. (because these old bombs are larger than what we use for tacticals) Not creating and delivering new nukes. Just retro fitting the ones we already gave them decades ago.

The F-15's carrying the bombs will be easy targets for Russian S-400 aa missiles

From over 20000 ft? Lol

Easily from 20,000 ft.

This isn't 1917 anymore Wilbur.

20,000 ft isn't all that high.

Maybe you should read up on s400 dumb fuck