Well here is a list of the main country's that will effect the us and in what way

 

United Kingdom

The UK will most probally be one of the most powerfull out of the counrty's they would most likly use there special force's (SAS) (SBS) ext to take out military leader's so it will make it more difficult for the us to interact to the war and there navy, Air force and army wont have a clue what there doing they also have military leaders what know what there doing and also the royal marine commando's and british paratroopers would p*** off the US quite abit.

 

India

They have a very populated army they lack on equipment although they strengthen in training much like the uk so they would most probally go into the heart of the US in main city's such as new york, washington ext

 

Russia

There Soldiers would be highly afficent in the war there job would be not to attack major city's but major buildings the one's that would be protected very well such like the pentagon and the wight house They would also use there navy to stop any cargo or us naval ship passing through.

 

China

Defonatly the best out of the lot lack in training and equipment but there's a f*** load of them these along with india would attack major city's.

They would also cut off supply's to starv them.

 

France, Germany and israel

These would probally take out us military base's using the french air force the german army and the israile special force's

 

Preaty much the US vs EU alone wouldent stand a chance let alone asia and the EU id say within the first month they would be wiped out not saying they have a bad military still the best in the world by far just speaking realisticly

One thing I think is missing here is who fired the first shots.

If the US i think would be very hard on the rest of the world.

I would think that naval forces and air forces would be hit hard.

I also think that the reasons for the war would matter on both sides.

If something like a 911 attack on either side would affect the resolve of the people.

But this war would never end in total victory for either side.