Are submarine launched ballistic missiles still inaccurate?

Question

In the early 1980s documentary First Strike, one of the arguments made for the development of the MX missile program was that in the event of a massive Soviet attack on the land-based missile and bomber forces of the United States, the SLBM force would be "too inaccurate" to effectively target the Soviet strategic missile force. This inaccuracy would mean that the SLBM force would be restricted to targeting "soft targets" such as cities, air bases, and ports.

What was the cause of the inaccuracy of the SLBM force compared to the land-based ICBM force, and does this difference still exist today?

Answer 1

Ballistic missile delivery depends very much on knowing exactly where you are launching from. Early SLBM launch platforms had typical positional uncertainties of 100's of metres. As the missile and any MIRV warheads were just unguided projectiles launch positional errors magnified and the resultant destination error could be very wide.

Land based missiles were preferred as the launch position was known accurately but vulnerable to first force strikes.

Modern SLBM platforms know their position to some centimetres allowing better accuracy and reduced yields for smaller targets. Modern missiles can partially correct for early launch drift, first stage drift by star sight observation reducing the error probability at target by orders of magnitude.