Ask Lemmygrad

Most major US bases have a long history of atrocity complicity and imperialist utility, like the Kadena AFB and other bases in the occupied Ryukus or Guam or the joint UK/US Diego Garcia base in Chagos. You'll probably be able to better orient yourself with a more general overview, however.

David Vine is a notable author and subject matter expert on the topic. He's a soc dem rather than a leftist, but this just means you can reference his work to a general audience without them flinching in terror or cite it in an academic paper if you need to write one since they're published by university presses. I recommend his 2020 book "The United States of war: a global history of America's endless conflicts, from Columbus to the Islamic State," which you can find on various online repositories like Anna's Archive/Z-Library. His website has a great deal of US base world maps and he has an excel spreadsheet where he tries to track all publicly known US bases worldwide.

He also wrote a 2009 book "Island of Shame: The Secret History of the U.S. Military Base on Diego Garcia" specifically on the occupation of Mauritius' Chagos (which incidentally was just recently compelled to sign an unequal treaty with the UK to convert the base into a Hong Kong-style colonial leasehold).