Русско-англо-русский юридический словарь

act of terrorism – the calculated use of violence (or the threat of violence) against civilians in order to attain goals that are political or religious or ideological in nature; this is done through intimidation or coercion or instilling fear (vocabulary.com)

The US State Department has described Saturday's knife attack which killed 29 people in China's Kunming city as "an act of terrorism". (BBC News)