War is a tricky thing. Vietnam didn't fall even after fighting countries for 39 years from 1940 to 1949. America fought many years in Korea too. America fought many countries. Russia was bad but America did not like try to take down Russia directly some might say. America fought countries in the Middle East for decades but then those countries got worse. America could win if they nuke Iran and kill 90 million Iranians but that would be a bad idea as that would inspire millions of terrorists globally to blow up many people in many countries around the world. Terrorists love to have excuses to strike back. Terrorists love to be martyrs, they love to be victims. So, countries like America can kill a lot of people with bombs but that would be a bad idea.