I don't think the sleeper cells operate independently from the "mother ship" or the other cells. Geez, think of the chaos if this were true, not to mention the attention and risk of discovery. Thought I read somewhere that they wait to receive specific orders and then carry them out.
Gee I have heard the EXACT opposite. Why call them "cells" if you expect them to operate as a group with a specific chain of command? Each time there is contact between the chain of command or between individual cells, the odds of compromise go way up.
Go read the Special Forces Operational Handbook, available from Paladin Press. Another great book is: "To Break a Tyrant's Chains" by Duncan Long also available from Paladin. I learned all of this not from books but as a US Army Officer, however.