Can hippos take over the world?

The old Khmer Kingdom in what is now Cambodia had an elite Flotilla of Hippo Subs as far back as the 15th century. This is all the more remarkable as Cambodia has no native Hippos. The subs were pretty substantial as they carried a crack crew of about 15 Hippos armed to the teeth with semi-automatic weapons. The West has tried to suppress this information for years as they fear that there are clandestine fleets of Cambodian Hippo subs still operating in Far Eastern waters. A terrifying prospect for western defense.