So you're a super power, you've got all those expensive nuclear weapons sitting around, and no one wants to play ball with the whole "let's fry the planet" idea. What to do? It really boils down to variations on one thing; making bloody big holes in stuff (see picture, credit wikipedia: the largest man made crater in the US).
There were various schemes for using nuclear bombs to make artificial harbours and canals, but the idea that beautifully sums up the bare faced hubris of humans is using nuclear detonations in a process I understand to be vaguely similar to todays fracking. I think you would be hard pressed to come up with a single better example of why humans do not deserve stewardship of the planet.
The concept was to use the force of an underground nuclear blast to crack open gas bearing rock and mine the results. Just the symbolism alone is enough to make you wonder how this actually got to the testing stage; "hey guys, lets poison our soil and water so we can get at this natural resource and use it to poison our air!"
I may not be a mining engineer, but it also strikes me that the possibility of radioactive natural gas burning out of control isn't something you want to be messing around with? Anyway, people realised after a while that this probably wasn't going to end well and gave it a miss, going back to desecrating the ecosphere in more conventional ways.