A program for the Small ICBM (SICBM) was started and proceeded to test firings from canisters (like the Peacekeeper), called Canister Assembly Launch Test Program (CALTP; note the same name and acronym were applied to such tests for the Peacekeeper missile as well). The program was terminated in 1992. The missile had earned the unflattering nickname "Midgetman". One designation was MGM-134A.
Like the Peacekeeper, the SICBM would have been cold-launched, i.e. it would be ejected from a cannister before the first stage motor ignited.
There were two test launches from Vandenberg: May 11 1989 and April 18 1991.