The Khmer Rouge had long viewed Phnom Penh's population with mistrust, particularly as the city's numbers had been swelled by peasant refugees who had fled the Khmer Rouge's advance and were considered to be traitors. Shortly after taking the city, the Khmer Rouge announced that its inhabitants had to evacuate to escape a forthcoming US bombing raid; the group falsely claimed that the population would be allowed to return after three days. This evacuation entailed moving over 2.5 million people out of the city with very little preparation; between 15,000 and 20,000 of these were removed from the city's hospitals and forced to march. Checkpoints were erected along the roads out of the city where Khmer Rouge cadres searched marchers and removed many of their belongings. The march took place in the hottest month of the year and an estimated 20,000 people died along the route. For the Khmer Rouge, emptying Phnom Penh was considered as demolishing not just capitalism in Cambodia, but also Sihanouk's power base and the spy network of the U.S. Central Intelligence Agency (CIA). This dismantling facilitated Khmer Rouge dominance over the country and enabled driving the urban population toward agricultural production.