The Vietnam syndrome is, as I understand it, the worries about the negative effect a war can have on the American population at large. The sentence says that this has disappeared and they are prepared to accept casualties and deaths in wars and conflicts. (BTW, I'm not American)
'Kraut' is a slang term for Germans, coming from the pickled cabbage they eat (Sauerkraut). Bring them on means that the speaker is ready to fight or argure with them and is confident of winning. 'Here we go' is something sung by English football fans, so if this is British English, it is a jingoistic (highly nationalist) statement by someone ready for trouble and sure of victory.
BTW, if it is BE, then it is sure to be followed up by recording how the Germans beat us, especially if it's football.