Country.

https://en.wikipedia.org/wiki/Country

Homeland defense

https://en.wikipedia.org/wiki/Homeland_defense

See also

• Airport security
• Civil defense
• High policing
• Infrastructure security
• Port security
• Supply chain security
• Boundaries of Security Report

U.S. specific:

• Homeland Security Act
• Homeland defense
• Center for Homeland Defense and Security (in California)
• Terrorism in the United States
• Texas Virtual Border Watch
• Surface and Air Transportation Programs Extension Act of 2011