Hackers are coming to Ukraine’s aid in an effort to target Russian government websites and officials with disruptive counterattacks, according to six people involved in the activity.

On Ukrainian internet forums on Friday, groups of Ukrainians who worked in the country’s technology sector shared information on how to launch distributed denial of service attacks, known as DDoS, and deploy malicious software targeted at Russian military officers and government officials. Some hackers from outside Ukraine have signed up to help too.

Several Ukrainians with computer expertise said they had joined a group of "cyber volunteers” who plan to use cyberattacks to fight back against the Russian military’s invasion of the country.