Why American entry looks likely

The scenario assumes Washington would not want a victorious Royal Navy to become the overwhelmingly dominant Pacific power while the United States stood aside. A British victory would extend European predominance across the Pacific as well as the Indian Ocean, Africa, and Europe. Japanese attacks on British and American shipping also create a political opening for intervention. Entry would still require a political decision, but Pacific power politics and public anger make alignment with the Allies much more plausible than alignment with Japan.