There's this organisation, which has a global system of secret and sensitive military bases situated in various geopolitical regions, not unlike those of the US military. One military installation is a naval base located on Île Pott (an island 271 kilometers north of New Caledonia), which is within reaching distance of Vanuatu, Fiji, New Caledonia, Samoa, Tonga, Papua New Guinea, New Zeland and Australia.
Although, I am somewhat concerned that Île Pott is not big enough to support a considerable fleet of vessels (of unknown makeup and size) along with a population of 800,000 soldiers and unspecified number of civilian personnel. This is because Panan has a length of around 7.17 kilometers (if Google Maps is to be taken at face value) and naval bases require a great deal of land to be built on.
I have toyed with the idea of having the base staffed by a skeleton crew of several thousand soldiers and civilians while the 800,000 troops are kept in cryostasis. When half of the fleet is mobilized, 400,000 of these soldiers are transported on-board while in cryostasis and woken up upon reaching their destination. While the other 400,000 are kept back at Panan in cryostasis, as reserves or "insurance" against would-be attackers trying to assault Panan.
Which only leaves the issue of maintaining the fleet and hiding it from prying eyes. How would such an issue be resolved?