well, it's far less cold than it used to be, despite the letest rattlings from russia. US and russia now sogned another agreement to get rid of some of their stockpile. I think russia and US are quite-ish happy with the current status quo.
Why shake the bees nest by creating am orbiting nuke? By doing that US basically tells the world it's not giving a damn about the treaties they agrees to and all hell will be breaking lose (russian, china, etc all putting nukes in LEO, seeling nukes to countries that should not have it, etc, etc)
Especially as mentined elsewhere, they already pretty much have this cabability with subs.
They might use it with things like a MOAB is similar but bigger in there, packs quite a punch as well