The designation "Keter" is assigned to subjects that both (a) display vigorous, active hostility to human life, civilization, and/or spacetime, and (b) are capable of causing significant destruction in the event of a containment breach. Such subjects must be cataloged, contained according to special containment procedures, and destroyed, if possible.
Merely being inimical to human life is not in itself cause for classification as a Keter-level object. A Keter classification indicates that not only is this subject capable of inflicting devastating harm to human life and civilization, but that containment protocols must be extensive, involved, and precisely followed in order to prevent it from doing so. Research into the neutralization of Keter-class SCPs is always a top priority for the Foundation.
Cases where Keter-class objects that can be neutralized by Foundation personnel persist in Foundation custody are rare, and are grouped into three main categories. In addition to cases where destruction of the object continues to be unfeasible due to apparent invulnerability or similar circumstance, there are some Keter-class objects with significant tactical value for the Foundation, as well as Keter-class objects that threaten more harm to humanity from their neutralization than from their continued existence.
The Foundation has harnessed some Keter-class SCPs, but such situations are rare exceptions: for example, SCP-076-2 only agreed to work with the Foundation due to its unusual relationship with Agent [REDACTED], and its ability to communicate with us, and even that didn't last. The majority of Keter-class SCPs are insentient, and most are inanimate objects. This status may change as research and discovery continues.