Washington doesn't announce that it is part of the alliance, which led by Saudi Arabia to wage war against the Houthis, then it does not upsetting Iran.
Washington announced its full logistical and intelligence support for Saudi Arabia in this war, so it ensures Saudi encouragement.
If the results of war which led by Saudi Arabia is good and makes achievements and be the winner against the Houthis inside Yemen, so Washington will have an important site such as Yemen. It is as anti-policy.
If this war make Saudi Arabia ready to negotiate to create better conditions for Saudi on Yemen situation. Washington gained a political solution in Yemen keeps its role in it.
If Saudi Arabia had failed and was involved in the war and suffered losses and began to cry, however, Washington will save it by Iranian – Yemeni negotiations by conditions which are refused by Arabia.
Washington continues its negotiations with Iran to reach understanding on the nuclear file.
The alliance which is led by Saudi Arabia on Yemen is a regional negotiator for Iran and the balance of power on Yemen will determine the negotiation between them. In both sides, the United States will be the winner.
Washington tries to have cooperation and negotiation and gain in both cases, and on both fronts.