 This policy meant that Singapore could quickly mobilise enough defence forces to deter any invasion, especially against Indonesia during the Confrontation, when the British withdrew in September 1971.Females were left out of national service—the explanation being that, during a time of war, they would be required to support the economy while the men were fighting.This policy is sometimes questioned as being sexist and has been discussed in the mass media a number of times together with the length of training involved.