It was true when Nixon first spoke of a silent majority. It was true when the US elected leader after leader on a platform of prolonging or escalating wars in Iraq and Afghanistan.
Even WWII wasn't popular in America until you were in it:
https://news.gallup.com/vault/265865/gallup-vault-opinion-st...
The only unforced delay there has been on a military adventure since Bush Sr. pulled out of Iraq was Obama resisting interventions in Syria and Ukraine that were being heavily lobbied for by both his and his opposite party. Immediately reversed once he had one foot out of the door, and he had made up for it by bombing everyone else.
America, and I mean its electorate, finds joy in murdering nonwhite children, or Slavs, or really anybody that speaks in a language that sounds funny or gutteral. It makes us feel safe. They'll know not to mess with us, because they know we're not afraid to murder even the most innocent and saintly civilians. We'll give them the Nobel Peace Prize and kill them 10 years later. We'll give people the Nobel Prize who kill children. We'll hear about atrocities in Venezuela and wonder how we should invest.
This seems difficult to falsify. I can think of a number of recent post-9/11 potential flashpoints that have been avoided by politicians due to the current unpopularity of foreign intervention.