Upon examining the map of Australasia, it becomes clear that the Philippines are like a nail hammered into the Southeast Asian region, making it a forward outpost for the United States on the western coast of the Pacific Ocean, threatening East Asia and Australia.
Arthur is keenly aware of the principle that one mountain cannot contain two tigers and naturally wouldn't allow the United States to have an outpost in the Southeast Asian region to counterbalance Australasia.
Putting it lightly, the Philippines is a transit station and supply point for U.S. warships, and a springboard on the western coast of the Pacific Ocean for the United States.
If stated more gravely, once the United States possesses more powerful airplanes, they could even fly from the Philippines, threatening Australia's colonies and native lands.
