Memento Mori

Memento Mori is a newly built particle beam cannon that was installed onto the lower orbital ring of the solar satellite system in Gundam 00. The cannon has the destructive yield of nukes (how many Hiroshimas is unclear) to instantly vaporize an entire country off the map.

Memento mori is a Latin phrase that may be translated as "Remember that you are mortal," "Remember you will die," "Remember that you must die," or "Remember your death". It names a genre of artistic creations that vary widely from one another, but which all share the same purpose, which is to remind people of their own mortality.

Development
It's unknown when was Memento Mori designed or built, but Innovator's Ribbons Almark forwarded the technology to the Federation for development. Wang Liu Mei was Ribbon's sponsor for the project in their mutual beliefs to Aeolia Schenberg's plan for planetary unification and preparing humanity into space.

Destroying Seel
To accelerate the unification of the world, Ribbons decided to activate Memento Mori to test its capabilities and wipe out the Seel Kingdom (last country(s) left to oppose the Federation) at the same time. A-Laws successfully vaporized the Seel Kingdom instantly with a single blast, taking several nearby Federation Army units as well.