Commodities. They power the economy and they're worldwide. Ofc you want the free flow of goods. From the US's perspective who cares who runs what nation, as long as its not hostile and its stable then the commodities can flow from it. Then manufacturers can make whatever they want to create products to generate growth and wealth, the vast majority of which flows into the US and into their stock market.

As it stands the war in Iran is creating problematic issues with many petrochemicals and their derivative products making it harder for countries to generate wealth to invest in the US stock market.