How so?
If you visit a foreign country, you are making an explicit choice to enter their jurisdiction.
If you are extradited from the US, it means the government (your representatives) explicitly chose to cooperate with another jurisdiction in some manner.
The current case is somewhat confusing to me. The US doesn't participate in the ICC. The matter to be investigated apparently occurred in a country that does participate though. But the suspects were part of an active military operation. Unlike a tourist, it doesn't really seem like armed forces are usually subject to the laws of a jurisdiction they might "visit" during combat (typically quite the opposite in fact).
If someone from outside your jurisdiction threatens your citizens, isn't any capable government supposed to take actions to protect them? To me, the real question here is why the US isn't part of an international effort to prevent war crimes.
That's not the part that's confusing to me. (I'm really not clear how you could possibly come away with that from what I wrote?)
The confusing part is the jurisdiction. In what capacity were the soldiers present in the other country? (It obviously wasn't voluntarily for leisure.) Based on the answer to the former, were they subject to the laws of the other jurisdiction at the time of their actions? Or do they instead fall under US jurisdiction? The US government's stance on this seems quite clear at least.
Current US government's stance is that war crimes by US soldiers are good celebration worthy thing.
US army itself is actually better then what that implies and does not have soldiers on the loose. But, we are talking about government here.