I shall begin with a most interesting historical overview:
The United States were begun on the foundation of Swiss Neutrality.... also called isolationism. This was the idea that any nation could keep politically to itself and not have to ally and treaty with any foreign nation. For instance: the Swiss have not fought in a foreign war (ie...out of it's borders) (or been attacked, for that matter) since 1815. (see hyperlink above)
This policy has been attacked by our people, our writers, and most shamefully, our Presidents. In an effort to control the entire Western Hemisphere (below Canada, that is) President James Monroe decided that American soldiers had the duty to fight to keep Latin America and the Caribbean free from any European influence. (ie....the USG would intervene by force if any European nation decided to colonize any new LA territories.)
This got us into the Spanish-American War, and we ended up taking ("colonizing") Guam, Philippines, Puerto Rico, and Cuba.
When dear old Teddy got into office, though, things began to change. Mr. Roosevelt was what is now called a "progressive". A "progressive Republican" of those days was basically a Democrat. T.R. decided that this doctrine needed enlarging. He invented what is now called the "Roosevelt Corollary". This new extension:
Yeah....what an amazing legacy! McCain will definitely follow in TR's footsteps!
Tr. himself used this to get into Cuba, and other LA nations. (in politically correct terms: "help them pay their debts and stabilize")
Herbert Hoover approved and released a Memorandum later which said that the "exercise of an international police power" was the "right of America as a state".
Now, it has been used many times in such unConstitutional means as any other President sees fit.
The Memorandum argued that the United States had a self-evident right of self-defense, and that this was all that was needed to justify certain actions.........
So you see....there is no doubt that as a President, McCain would expand the use of American soldiers to protect "American interests" (read: things/places that the USG doesn't think other nations should have/own) all around the world.