plus what nukes would they use. mini nukes arent enough to blow the world back to the stone age (again).
plus one of the reasons they are so low on recourses is that they have to fight off jerks like the legion
They are engaged in a war, which is inevitable when your policy is such aggressive expansionism. Also, they are fresh off the heels of another war, with the Brotherhood. So far they ain't doin' so hot a job of "keeping the peace".