Considering homeland security. What are the top three hazards we face?

The world encounters a never-ending variety of hazards. What do you consider the top three hazards we face? You should consider this at any level you wish: local, regional, state, national, or global. Be sure to state which level you are operating from. For each hazard, briefly discuss several mitigation strategies you would recommend. Support with 2 sources. About 300 word count needed.