The cost will probably cost trillions of dollars and thousands of lives over many decades.
The cost of doing nothing now could be the end of freedom and if Russian tendencies toward aggression cannot be contained possibly the end of human civilization and a tendency to glow in the dark.
Welcome to Cold War II.
if the cost is going to be trillions of dollars, does the US government raise taxes or grow the deficit further ?
So the first Cold War was won; so why do you think Russia wants another cold war ?