A Defense Umbrella?

Here’s something that I don’t understand: The United States currently maintains 4 major proxies in the Middle East. Between Israel, Iraq, Egypt, and Saudi Arabia we’ve managed to cover a huge proportion of the region’s population, territory, oil reserves, and military capability. In addition to these four major clients, we probably have half a dozen minor clients. The “US client-to-state-ratio” in the Middle East has got to be the highest in the world. Given this, why is it always necessary to further proclaim defense “umbrellas”? Don’t patrons have clients for a reason? And don’t clients have patrons for a reason?