US military personnel may be portrayed by their critics as unthinking killing machines, but in training their officers, the US puts a focus on teaching not just military strategy but critical thinking, history and philosophy.

In the third of his reports on the US war machine, North America editor Mark Mardell investigates the US's increasingly intellectual approach towards warfare, counter-insurgency and grand strategy.

Listen to Mark Mardell's reports from the US on the "military-industrial complex" and the nation's "fierce gratitude" for their troops or read more and join the debate on his blog.

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