In 2003, Weather Underground members stated in interviews that they had wanted to convince the American public that the United States was truly responsible for the calamity in Vietnam. The group began striking at night, bombing empty offices, with warnings always issued in advance to ensure a safe evacuation. According to David Gilbert, who took part in the 1981 Brink's robbery that killed two police officers and a Brinks' guard, and was jailed for murder, " goal was to not hurt any people, and a lot of work went into that. But we wanted to pick targets that showed to the public who was responsible for what was really going on." After the Greenwich Village explosion, in a review of the documentary film "The Weather Underground" (2002), a "Guardian" journalist restated the film's contention that no one was killed by WUO bombs.