This question is 100% a provocation. Trump got democratically elected and thousand of soldiers carried out his orders while they could have refused. Now that USA government has made his own “military special operation” are we going to be racist with americans and treat them like russians? Calling them orcs or implying the population is all shit?
Regarding the soldiers refusing - https://youtu.be/TwPLqGkYnBA is worth a watch. Not as straightforward as you imply.
So i guess the US government is as much shit as the russian one threatening soldiers for refusing orders.
Show me a single military that doesn’t punish dissenting soldiers.
German soldiers can refuse orders under certain conditions (e.g. if they against human dignity)