You ask "for what?", I'll tell you what I believe is Trumpet's motive. He wants to believe that he is a more powerful leader than Putin and he hates the reality that he is restrained by his critics at home. Putin controls nearly all the money in Russia and Trumpet only controls a tiny percentage of US wealth. 
The ego battle between these maniacal oligarchs is intense and extremely detrimental for both countries. Trumpet has more guns but Putin has more control. They both want the most guns and the most control. This rattling of sabers is not a good situation for our troubled world.