> I'm sure once upon a time no one in their right mind considered Japan attacking Pearl Harbor a realistic possibility (as in "zero chance" to use your words),

> I'm sure once upon a time no one in their right mind considered Japan attacking Pearl Harbor a realistic possibility (as in "zero chance" to use your words), yet it happened. Doesn't have to be China at all - I just used it as an example of a country currently building artificial islands for military purposes and how taking an island with no military presence (US has left, remember) would be easier than building your own. It's a very strategic location. The attack on Pearl Harbor only worked because they managed to do it in secret. It would have been suicidal and a disaster otherwise. The US overestimated it's intelligence capabilities, but they were right to think it was an improbable attack. Nowadays this wouldn't work. China's islands are very close to it's territory, and were preceded by 50 years of claims in that area. > Again, it doesn't have to be China Who else? > Why would the US Territory of Guam come into play if the US gave up Hawaii and it was no longer a part of the US to defend? For multiple reasons. Firstly, it's going to be impossible for the Chinese to actually hold Hawaii if Guam and it's related island chain is under US control and operational militarily. Fully impossible. Second, if the Chinese indeed managed to fully take Hawaii, Guam becomes completely indefensible. So the US is essentially obliged not to let Hawaii come into Chinese hands or it's entire military position crumbles. Thirdly, an invasion would be obvious and Guam is in a really good position to deny it.