In 2007, a nation was hacked offline via inaccurate information in their news cycle which caused protests that devolved into rioting. Then before the government could counter the inaccurate information, their media and power were hacked offline including all government websites.
https://www.bbc.com/news/39655415
In 2015, the Ukrainian power grid was hacked offline.
https://www.wired.com/2016/03/inside-cunning-unprecedented-hack-ukraines-power-grid/
In 2018, the Secretary of the Air Force announced cyber was a new warfighting domain joining air, land and sea. https://www.fifthdomain.com/newsletters/digital-show-daily/2019/09/20/how-the-air-force-has-reorganized-its-cyber-staff/
This website calls it the 5th domain because space is also considered a warfighting domain.
However, information remains a contested space which is not yet formally labelled a warfighting domain.
35-Year Public Affairs & IT Professional 