You wouldn't hear any opposition from inside the USA.
At the same time, the USA levelling the place would create a lot of opposition basically everywhere else.
The UK government trying to toe the line with the USA about invading Iraq in the name of the GWOT was met with 10-16% of the UK population marching in protest against UK involvement: https://en.wikipedia.org/wiki/15_February_2003_anti-war_prot...
This is something I bring up whenever anyone can't understand why Israel's response to Hamas' attack nearly two years ago now is likely even stronger than the USA's to 9/11 — even at best it would take a decade for the rage to dissipate, and the Israeli people are unlikely to care about the opinions of people like me for the same reason the Americans didn't.