Bunker Cluster

The Bunker Cluster (バンカークラスター) is a cluster munition warhead developed independently by England that releases hundreds of explosive shells that are made to pierce into underground weapons. So fearsome is the weapon that under the influence of the Roman Catholic Church, the European Union forced England to sign a treaty to ban the weapon.

The weapon is later used under Carissa's coup, the British Halloween, for the first time since the ban, most famously in the Battle of Buckingham Palace.

Principles
Developed using technology original to England, the warhead is often equipped on cruise missiles, allowing for a quick delivery of the warhead to its destination as it is fast enough to near Mach 5 at low altitude, not taking even a minute to travel 1000 kilometers.

When used, the warhead spreads around 200 special smaller shells that are made to piece a military shelter 50 meters underground. The detonation depth of these shells can be timed however. The warhead is powerful enough blow away an area with a radius of 3 kilometers in every direction.

Treaty
Several years prior to the British Halloween, with the influence of the Roman Catholic Church, the European Union adopts a treaty that specifically banned the weapons the country has been developing. The country's nuclear weapons were banned, while France, not only being able to keep their nuclear weapons intact but had received all of the United Kingdom's nuclear weapons under the treaty. The official reason given was because as France would be the sole possessor of nuclear weapons within the EU they would therefore have the technology needed to safely disassemble them. Moreover, this also includes the Bunker Cluster warheads, though that didn't stop the country from continuing its development.

By the start of the British Halloween, several warheads have already been developed and are ready for use by the military.