Original sentence: Where the prior coupling of Canada Customs with the Canada Revenue Agency lent itself to a focus on tax collection, the new Agency was created to address heightened security concerns post-9/11, and to respond to criticisms, mostly from the United States, that Canada was not doing enough to ensure the security of North America
Edited sentence: Where the prior coupling of Canada Customs with the Canada Revenue Agency lent itself to a focus on tax collection, the new Agency was created to address the realities of security in the post-9/11 world, and to respond to criticisms, mostly from the United States, that Canada was not doing enough to ensure the security of North America