From a story on cjr.org by Mathew Ingram headlined “One year from Russia’s invasion of Ukraine, where does the ‘cyberwar’ stand?”:

After Russian troops invaded Ukraine a little over a year ago, the latter country set out to reinforce a second front in the war—a digital one. As I reported for CJR at the time, the Ukrainian government posted appeals in online hacker forums, asking for volunteers to protect Ukrainian infrastructure and conduct digital missions against Russia. The posts asked hackers to “get involved in the cyber defense of our country.” According to Foreign Policy, within a couple of months, more than four hundred thousand people had joined the informal hacker army.