One of the major factors that led to the downfall of Germany in WWII was that the Japanese attacked America instead of Russia. if russia had been forced to wage war on two fronts they likely would have lost. American isolationist policy would have lasted untill the soviets and europe had fallen. without allies and with no place to land in europe, waging war on two fronts america would have fallen. the current language would depend on whether the german or japanese armies had taken higher losses. the nation with the advantage would have declared war, and conquered the other. the world would have been unified under a terrifying and cruel facist rule. as far as an american war with china, the result was made apparent during the Korean War. more advanced tech, artillery, and air supremacy versus 3/4 million guys with soviet era armaments will end in a long drawn out conflict that will cripple and destroy both involved parties(100 years war), or internal pressure on both sides would force some sort of a peace resolution. America's war record is not perfect, but every nation loses wars. Rome, the nation that in my humble opinion was the most powerful nation of all time(not called the eternal empire for no reason), had much greater defeats than Vietnam. i hold up for example the legions that they sent to quell the rebellions in gaul. four legions were decimated, with nearly no survivors, trying and failing to conquer it. they were slaughtered with nothing to show for it. about 20,000 men in an era where to kill someone you had to stab them, and factoring in population differences between 1960's america and rome, is a worse defeat than vietnam. (yet again, in my humble opinion) not to say vietnam wasn't a defeat. 1812, however, was not a complete defeat. america remained a nation. having the capitol torched doesn't mean defeat. if it did, britain lost WWII. the capitol was bombed and buzzed worse than washington was burned in 1812. somalia was a lack of effort and a politician who spent 2102400 minutes in his term trying to get reelected.(for those of you who are lazy, that is 35040 hours or 1460 days or 4 years or his whole term) bay of pigs was the mentally retarded brainchild of kennedy and the CIA director. not america's most brilliant moment. in summary, post vietnam american defeats have been caused by selfish politicians and low levels of public support. History lesson/Insane rant is over.