Most militarily-significant targets are themselves non-military.
The Russian war of aggression on Ukraine is a prime example: power infrastructure, transportation, communications, commercial hubs, healthcare, and general civilian targets of opportunity are all targeted with high frequency by Russian forces.
UK national security interests are spelled out in summary beginning on page 5 of this PDF, "Government Functional Standard: GovS 007: Security", notably
Each organisation’s governance and management framework shall cover physical, personnel, cyber, incident management, technical and industry security
As an example of non-military focus, the present US national security policy leads with ... tourist visas:
To protect Americans, the United States must be vigilant during the visa-issuance process to ensure that those aliens approved for admission into the United States do not intend to harm Americans or our national interests.
An earlier document from the Bush II White House leads with:
People everywhere want to be able to speak freely; choose who will govern them; worship as they please; educate their children—male and female; own property; and enjoy the benefits of their labor.
Originally conceived as protection against military attack, national security is widely understood to include also non-military dimensions, such as the security from terrorism, minimization of crime, economic security, energy security, environmental security, food security, and cyber-security.
> Most militarily-significant targets are themselves non-military.
Indeed. Large scale war is extremely expensive. Russia's government is spending about 40% of total tax revenue on invading Ukraine. So anything it can do to harm the economies of the people fighting it helps. Equally, this is why Ukraine has been putting so much effort into blowing up oil and gas infrastructure in Russia, their #1 source of tax revenue.
The Russian war of aggression on Ukraine is a prime example: power infrastructure, transportation, communications, commercial hubs, healthcare, and general civilian targets of opportunity are all targeted with high frequency by Russian forces.
UK national security interests are spelled out in summary beginning on page 5 of this PDF, "Government Functional Standard: GovS 007: Security", notably
Each organisation’s governance and management framework shall cover physical, personnel, cyber, incident management, technical and industry security
<https://assets.publishing.service.gov.uk/media/613a195bd3bf7...> (PDF)
The US electric grid has also been of significant concern. Ted Koppel's book Lights Out (2015) addressed this specificly:
<https://news.wttw.com/2015/11/09/ted-koppel-americas-vulnera...>
As an example of non-military focus, the present US national security policy leads with ... tourist visas:
To protect Americans, the United States must be vigilant during the visa-issuance process to ensure that those aliens approved for admission into the United States do not intend to harm Americans or our national interests.
<https://www.whitehouse.gov/presidential-actions/2025/01/prot...> (20 Jan 2025)
An earlier document from the Bush II White House leads with:
People everywhere want to be able to speak freely; choose who will govern them; worship as they please; educate their children—male and female; own property; and enjoy the benefits of their labor.
<https://georgewbush-whitehouse.archives.gov/nsc/nssall.html> (2002)
Wikipedia's National Security article notes:
Originally conceived as protection against military attack, national security is widely understood to include also non-military dimensions, such as the security from terrorism, minimization of crime, economic security, energy security, environmental security, food security, and cyber-security.
<https://en.wikipedia.org/wiki/National_security>