I'd say it would be quite difficult to foment anti-war sentiment in the same way as the Vietnam War era. The West capitalised on 9/11 and was able to very effectively sell the Iraq War (and subsequent wars) to the public because of this. I don't think there was anything quite like that even in red scare terms for Vietnam.
Plus, another crucial difference is that Vietnam War-era America had conscription with roughly one-third of America's military personnel being conscripts who were drafted, it's generally a lot easier to get people to be against something when it obviously infringes on an individual's ability to choose to not participate without consequence. Nowadays though, it's an all-volunteer force that is very unlikely to be receptive to the same messaging.
This is where you lost me. I only ever seen this get brought up when it comes to defending the "troops". Funny how it's always like this. If someone complained about Communists "demonising cops/ICE" they'd rightly get made fun of as a lib who is indifferent to the nature of these positions. But it's specifically a sticking point for you that Communists aren't saying "thank for your service" to a glorified contract killer.
Also no, American troops aren't responding to their material conditions. The vast majority come from fairly well-off backgrounds and enlist with the view that it's a chance to have an "adventure" or to "serve their country" (a country founded on slavery and colonialism). If I had to guess, the truth that you're indifferent to what the soldiers did abroad because it didn't happen to you is a fact that is deeply uncomfortable to you.