I happened upon this site while researching the situation in Syria in 2012/2013.
This article in particular provides the best overview of US military presence worldwide:
From their “About” page:
The Centre for Research on Globalization (CRG) is an independent research and media organization based in Montreal.
Since September 2001, we have established an extensive archive of news articles, in-depth reports and analysis on issues which are barely covered by the mainstream media.
This is an important website for analysis of current events.