That’s what they are doing. The Houthi’s in Yemen are allied with Iran. The problem is that we are the only country with any real military deterrent to Iran’s desire to close the Straits of Hormuz-through which the vast majority of the world’s oil still flows, hence the large coalition of countries when Iraq invaded Kuwait. I despise both countries and wish they would both disappear, but it’s more complicated than that.
The Saudis have a tidy income. Let them build or hire their own deterrent.
IF the Saudis don’t like what the Iranians are doing, there are plenty of oil terminals and pipelines for the Saudis to retaliate against.