The site is planned as an additional location, close to the equator, with launch arcs that can look east - maximizing launch capability. Original discussions involved air-launch of a Polyot launcher, but fell apart due to treaty restrictions over technology transfer. More recently the Indonesian government has been trying to entice SpaceX to bring Falcon 9 launches to the proposed site.
Proposed as far back as 2006, there have been pulses of interest or advertisement in 2019 and 2023. No ground has yet been broken.
