Nanomachines can heal or destroy; Donald says both kinds occupy his blood and that lethal outside machines are pumped into silos.
Microscopic machines in blood are intended to repair the cellular damage caused by freezing and thawing. Outside, invisible machines move on the wind, destroying human things and returning the world to wilderness. Donald realizes that each cleaning releases more nanos into the outside world.
Paul Thurman describes destructive and protective machines fighting inside Donald and warns that the conflict will devastate his body. Donald now confirms that his blood contains both healing and destructive machines. He explains that the machines outside are pumped into silos to destroy their inhabitants and recalls first learning of nanos through an Iranian effort to target an ethnic group.
They are both agents of medical repair and the destructive mechanism Donald identifies behind silo shutdowns.