Officials gathered at the Aspen Institute's annual security forum in Colorado Thursday discussed both internal and external threats to the United States, including threats from natural disasters, a report on the Defense Department's Web site said.
Paul Stockton, assistant secretary for Homeland Defense and Americas' Security Affairs, and Michael Sheehan, assistant secretary for Special Operations and Low-Intensity Conflict, said much remains to be done to protect the country, both from terrorism and natural disasters.
Citing the 2009 attempted bombing of Times Square as an example of internal threat, Sheehan warned adversaries, whether state or non-state, are clever and adaptive.
"Rather than attacking us on the pointy end of the spear ... there is a risk that they'll adopt a profoundly asymmetric strategy, reach around and attack us here at home [in] the critical infrastructure that is not owned by the Department of Defense," he said.
Sheehan said the United States and its international partners have made much progress in the fight against al-Qaida and its affiliates.
Stockton warned of the possibility of prolonged power outages.
"There is a problem I discussed last year that is still keeping me up at night, and that is ... the risk of a long-term, large-scale outage of the electric power grid," he said, noting such outages could result from a natural disaster or from a targeted attack.
Sheehan and Stockton said the Defense Department is continually developing partnerships, both with the international community and with U.S. industries, to fight these threats. Stockton said industry needs to have strong plans to ensure the continuity of operations in the event of an emergency.
Celebrity Families of 2014 [PHOTOS]