(Answer, according to Thomas Sowell: "'It’s hard to know how many people could possibly have foreign policy experience before reaching the White House besides a secretary of state or secretary of defense. The last secretary of war (the old title of defense secretaries) to later become president was William Howard Taft, a hundred years ago. The last secretary of state was James Buchanan, a century and a half ago."
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Although I think Ike might be a good asterisk answer, too. Blowing up foreign armies would qualify in my book, LOL)
While I tend to agree with Sowel, I'd probably expand the field more, (foreign policy advisors, deputy and undersecretaries, ambassadors, CIA directors, military generals, etc).
His point still stands never the less.