by restoring Russia to the status of super power and hopefully making her the number one super power in the world. Their latest bid ended the Cold War and caused them to bankrupt their economy. He is a driven power hungry egomaniac who will stop at nothing to see that he gets his way.
He is obsessed with being able to defeat the US Missile Defense Shield which indicates to me that he has thoughts of conducting some sort of aggressive military action against us in the future. He has the absolute right to do whatever is needed to defend his homeland and I can even see why this would certainly be a prudent action. Imagine the situation that he would be in if this country had a Missile Defense Shield which could not be breached. It would certainly give us a military advantage which would be extremely troubling.
I would want the same thing if I were he, but I truly believe that his rationale for doing so goes far beyond looking to only defend the interests of his country. I believe that if he thought that he could successfully attack and subdue the United States and the rest of the free world he would not hesitate to do so. His powers as the President of Russia are somewhat limited but he has done everything possible to work around all restrictions and is now able to do just about what he pleases.
His actions are therefore prudent as they would be for any leader, but I sincerely believe that his motives are gravely suspect.