A pro-Islamic State (IS) Telegram channel advised IS supporters, particularly those residing in Belgium, on Operations Security (OPSEC) and other technical strategies for avoiding apprehension by authorities following the attacks on Brussels.

In reaction to police brutality, especially against protesters around the globe, the Anonymous hacking collective claimed to have disrupted 23 websites via Distributed Denial of Service (DDoS) and defacement attacks while leaking the databases of several police affiliated websites from Brazilian, French, Belgian and Italian domains.