American nuclear forces consist of ballistic missile submarines, land-based intercontinental ballistic missiles, and bomber aircraft.

Donald Trump ruffled Kremlin feathers last week, when he ordered two US nuclear submarines to move closer to Russia.

Russia has abandoned a long-held nuclear "freeze" after Donald Trump deployed submarines near Vladimir Putin's coasts. Moscow has said it no longer considers itself bound by a self-imposed ban on the deployment of missiles - and is poised to bring short- and intermediate-range nuclear weapons into action.