Elstak was born in the Dutch East Indies to Surinamese parents.

In the run-up to the independence of Suriname in 1975, Elstak was appointed as project officer for the transition of the TRIS to the Surinamese Armed Forces.

In subsequent years, there was much unrest in the Surinamese army, particularly in relation to working conditions.

The establishment of the BoMiKa was unacceptable to Elstak and Prime Minister Henck Arron.

Colonel Elstak was deposed by the coup perpetrators as commander and replaced by Bouterse.