Bruce Hoffman states: "Unlike many terrorist groups today, the Irgun's strategy was not deliberately to target or wantonly harm civilians." Max Abrahms writes that the Irgun "pioneered the practice of issuing pre-attack warnings to spare civilians", which was later emulated by the African National Congress (ANC) and other groups and proved "effective but not foolproof". In addition, Begin ordered attacks to take place at night and even during Shabbat to reduce the likelihood of civilian casualties. U.S. military intelligence found that "the Irgun Zvai Leumi is waging a general war against the government and at all times took special care not to cause damage or injury to persons". Although the King David Hotel bombing is widely considered a "prima facie" case of Irgun terrorism, Abrahms comments: "But this hotel wasn't a normal hotel. It served as the headquarters for the British Armed Forces in Palestine. By all accounts, the intent wasn't to harm civilians."