During the "Konfrontasi", where Indonesia openly opposed the formation of Malaysia, Indonesian saboteurs mounted a campaign of terror in Singapore. There were a total of 37 bombings from 1963 to 1966. They were trained to attack military installations and public utilities. However, when the saboteurs failed in their attempts to attack these installations that were heavily guarded, they set off bombs indiscriminately to create panic and disrupt life on the island. By 1964, bomb explosions became frequent. To help the police and army defend Singapore from these attacks, a volunteer force was set up. More than 10,000 people signed up as volunteers. Community Centers served as bases for the volunteers to patrol their neighbourhoods. In schools, students underwent bomb drills. The government also warned Singaporeans not to handle any suspicious-looking parcels in the buildings or along streets. Despite the efforts of the British, small groups of saboteurs managed to infiltrate the island and plant bombs. By March 1965, a total of 29 bombs had been set off in Singapore.