Four minutes to armageddon

Just one week into his presidency, on Jan. 27, 1969, Richard M. Nixon got an eye-opening briefing at the Pentagon on the nation's secret nuclear war plans -- the Single Integrated Operational Plan, as it was known then. "It didn't fill him with enthusiasm," Henry Kissinger, the national security advisor, said later. The briefers walked Nixon through the absolutely excruciating decision a president would face upon receiving an alert of impending attack: whether to launch nuclear missiles.

The slides used to brief Nixon that day have been partially declassified and released by the National Security Archive, and they suggest how complex the whole decision process would be.

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