Boomer warhead
From Supremacy Wiki
Launch boomer warheads
This allows a Superpower to launch warheads that have already been loaded onto a boomer during Phase 1. Warheads launched from a boomer have a range of 2 territories. L-Star blanket slots can not shoot down warheads fired from boomers. Each warhead fired a distance of 1 territory has a 20% chance of being hit by a single L-Star slot protecting that territory. If a warhead is fired 2 territories the chance improves to 40%. L-Star slots can hit one warhead.
If one or more warheads are remaining after the L-Star defense has taken place then the territory is nuked or neutroned, nuclear warheads are destroyed by L-Stars first if a territory is targetted by both types of warhead.
There are some examples here.