Lembaga Ketahanan Nasional (National Tenacity Institute) or in short, Lemhannas, is a Non-Departmental Government Institution whose duty is to carry out government stewardship in the area of strategic national tenacity/endurance research and training.

Lembaga Pertahanan Nasional (National Defense Institute) was established on May 20, 1965 based on Peraturan Pemerintah (Government Ordinance) Number 37, 1964, and directly reports to the President. In 1983, the institute changed its name to Lembaga Ketahanan Nasional, directly reports to Panglima ABRI (Chief of Staff). In 1994, the institure reports to Menteri Pertahanan dan Keamanan (Defense and Security Minister). Since 2001, Lemhannas became a Non-Departmental Government Institution directly responsible to the President.