http://www.greatamericannero.com/research/nrpresearch/index.htmfrom the National Response Plan....
"The President leads the Nation in responding effectively and ensuring the necessary resources are applied quickly and efficiently to all Incidents of National Significance.As necessary, the Assistant to the President for Homeland Security convenes interagency meetings to coordinate policy issues. Though White House-level coordination mechanisms are not described in detail in the NRP, all other Federal coordinating mechanisms and entities described in the NRP support, and are consistent with White House-level interagency coordination."
later on...
"A catastrophic incident, as defined by the NRP, is any natural or manmade incident, including terrorism, that results in extraordinary levels of mass casualties, damage, or disruption severely affecting the population, infrastructure, environment, economy, national morale, and/or government functions. A catastrophic incident could result in sustained national impacts over a prolonged period of time; almost immediately exceeds resources normally available to State, local, tribal, and private-sector authorities in the impacted area; and significantly interrupts governmental operations and emergency services to such an extent that national security could be threatened. All catastrophic incidents are Incidents of National Significance. These factors drive the urgency for coordinated national planning to ensure accelerated Federal/national assistance."
and
"Federal support must be provided in a timely manner to save lives, prevent human suffering, and mitigate severe damage. This may require mobilizing and deploying assets before they are requested via normal NRP protocols."