Vietnam was the last time we marched in the streets to protest US foreign policy.
There were a few protests around the Iraq War, but they were very weak. I know because I was at a few of those marches. It was incredible how hostile many of the people driving by were. Their faces would turn to hard stone hate when they saw us. Many people flipped us off and threatened us. When I opposed the ramp-up to the invasion and the invasion itself, I was repeatedly threatened by other Americans for not supporting the war. My own father, hardline liberal Democrat and fanatical Zionist, supported the war to the hilt and even threatened me for not supporting it.
I know some liberal Democrats who say, “I opposed the war!” but they were sheepish and more or less silent during the entirety of the war and seemed embarassed to come out against it. For the entirety of the war, I almost never heard one single comment from them against the war. When I called the war “a Nazi-like war of aggression,” I got a lot of animated reaction from liberal Democrats. Even today, they are very reluctant to talk about that war, and when you bring it, they first say they opposed the war, and then they go on to give all sorts of reasons justifying it.
In other words, the antiwar and certainly the anti-imperialist and anti-interventionist movement in the US is dead in the water. When even most liberal Democrats are jingoistic flag-waving exceptionalists, you know the country is history.