The Kremlin has revised its nuclear policy. Does that make the use of atomic weapons more likely?

Russia Nuclear - (Russian Defense Ministry Press Service)

The 4-year-old document has a bland, bureaucratic title — “Basic Principles of State Policy on Nuclear Deterrence” — but its contents are chilling, especially with its newest revisions.

Better known as Russia's nuclear doctrine, the revamped version that was signed Tuesday by President Vladimir Putin spells out the circumstances that allow him to use Moscow's atomic arsenal, the world's largest.