Why might the various forts have been built at their geographic locations

they were unable to pay their debts

the east coast has nothing to do with the dust bowl, the dust bowl killed a full year's worth of crops in seconds, and with the dust on the land, the land would be worthless.   furthermore the farmers couldn't  get  out of their houses due to the dust so when the bank came to collect money, farmers couldn't  pay it

so, based on the research i've done. the u.s. government were always on a wild goose chase just to take down castro. he then retired his trone to his brother raul in 2008 due to some health issues. so it's obvious your answer would be:

castro had no allies from which he could receive aid.

hope this and have a fantastic day!

                                                    -wolfiewolffromsketch