Oh, you are right. It was not the Americans. It was the British.
http://www.kanaanonline.org/articles/00361.pdf"Known in the West as “Ibn Saud”, the Wahhabi Imam Abdulaziz was well loved by his British masters. Many British officials and emissaries in the Arab Gulf area frequently met or interacted with him, and generously supported him with money, weapons, and advisors. Sir Percy Cox, Captain Prideaux, Captain Shakespeare, Gertrude Bell, and Harry Saint John Philby (the so-called “Abdullah”) were among the many British officials
and advisors who constantly surrounded Abdulaziz to help him with everything he needed. With British weapons, money, and advisors, Imam Abdulaziz was able to gradually conquer most of the Arabian Peninsula in a ruthless manner under the banner of Wahhabism to create the Third Saudi-Wahhabi State, known today as Saudi Arabia."
My mistake.