If the U.S. were to take on the rest of the world, they wouldn't be stupid enough to just declare war on every country in the world.
They would first use subtle diplomacy to gain a foothold in resource-rich weaker countries, like those in south america and canada. Who knows? A North-American Alliance, sorta like the Warsaw Pact?
Africa, South America, and the rest of North America would offer next to no resistance. We can invade them first (OH NO COLUMBIA IS GROWING DRUGS. WE CANT HAVE THAT. LETS INVADE THEM)
Next, if we were to stage an "incident", we could justify cutting off foreign aid to Russia. Let's see how long it takes for them to starve into surrendering.
Furthermore, if Asia sees that America is preoccupied with other parts of the world, Pakistan would declare war on India, and Taiwan, China, North/South Korea, would fight amongst themselves. If the U.S. is busy elsewhere, many countries will take the chance to gain more land for themselves
Also, the U.S. would have allies in the rest of the world too. (Great Britain, Japan, etc.)
You forget that America has heavy influence on the rest of the world. Many countries (Russia included) depend on America for foreign aid, and many would like nothing better than to suck up to the most powerful country in the world.
Another group of countries would remain NEUTRAL. They wouldn't take sides cause they're too weak or weak-minded.
On the Frenchies:
http://www.****************.com/text/france.html
With Russia starving, the rest of North America, South America, and Africa useless, and Asia fighting amongst themselves, and part of the rest of the world allied or neutral to the U.S., it'll basically be this:
U.S. vs. half of Europe + Russia + maybe some Asian or Middle Eastern countries.
![N[U]TS](/data/avatars/m/4/4610.jpg?1366521177){kind=avatar}
