Originally modelled on the pre-World War II national police force of Japan, the TNPD was reorganized several times to meet changing public order and internal security needs. American advice, training, and equipment, which were provided from 1951 through the early 1970s, did much to introduce new law enforcement concepts and practices and to aid in the modernization of the TNPD. During this era the strength and effectiveness of the police grew steadily.