This Global Research article by Prof. Jules Dufour provides an introduction to how the Untied States operates its military globally to provide control of commerce and military expansion and ultimately to secure power to Washington D.C.
This global nexus follows a strategy commonly referred to as Full Spectrum Dominance "whereby a joint military structure achieves control over all elements of the battlespace using land, air, maritime and space based assets."
Whether or not you agree a benevolent force ought to maintain full spectrum dominance (or that such benevolence is conceivable), it is near to pointless to attempt to grasp situations in areas of political unrest leading to military presence--like Pakistan, Sudan, Iraq, Kyrgyzstan, Georgia and the Caucasus or even Israel--without developing some understanding of the existing web of military strength and action that has been stretched around the globe by planning and construction that can appropriately be called empire building.
"The Worldwide control of humanity's economic, social and political activities is under the helm of US corporate and military power. Underlying this process are various schemes of direct and indirect military intervention. These US sponsored strategies ultmately consist in a process of global subordination."
Jules Dufour is President of the United Nations Association of Canada (UNA-C) – Saguenay-Lac-Saint-Jean branch and Research Associate at the Center for Research on Globalization (CRG). He is Emeritus Professor of Geography at the University of Quebec, Chicoutimi.
In 2007, Professor Jules Dufour became Chevalier de l'Ordre national du Québec, a distinction conferred by the Quebec government, for his contributions to World peace and human rights, his numerous scholarly writings and the work he accomplished in the context of national and international commissions on issues pertaining to regional development, human rights and the protection of the environment.
The Worldwide Network of US Military Bases; The Global Deployment of US Military Personnel