The Internet provides a medium for the rapid mobilization of dissatisfied citizens and potentially contributes to various forms of political instability, including terrorism. However, the spread of the Internet may not lead to a higher intensity of terrorist attacks because direct perpetrators rely on close personal offline ties, and the national security agencies derive symmetrical benefits from Internet development as terrorists. In addition, the number of connections proxies a general level of country development, which is associated with less terrorist activity. We analyze the relationship between the number of Internet connections and the intensity of terrorist attacks using time-series cross-sectional data from the Global Terrorism Database from 1970 to 2018. Estimation of negative binomial regression models demonstrates an inverse relationship between Internet proliferation and the number of terrorist attacks, which holds for democracies and is absent for autocracies. Our results suggest that Internet proliferation is not a decisive factor in terrorism activity. Its impact on terrorism depends on the type of political regime and the level of socio-economic development.