Yes, I know, but conservatism is so stupid these days that it doesn't even work within its own moral confines. You don't have to convince conservatives that conservatism is immoral, you can convince them that conservatism is counter to its own goals.

For instance, the goal of all the US' military interventions was to maintain our hegemony. You and I, of course, could point out that the wars and sanctions kill millions of innocent people, but conservatives don't give a fuck about anyone but themselves at worst, or their tribe at best, and certainly not the lives of soldiers.

In the case for our war with Iran, all we're doing is accelerating the decline of our Empire. There is literally no valid conservative argument to made, no matter how amoral, that continuing war with Iran is a benefit to the United States. We're moving our troops out of the region, eroding our soft power, the petroyuan is coming into being, our bond rates our rising, we are losing allies, governments that supported us (House of Saud) are in existential danger, etc. Conservativism is making the US objectively a weaker nation.