The U.S. Defense Security Cooperation Agency has notified Congress on the potential upgrade of 60 Singapore F-16C/D/D+ fighters. This notification contains additional requirements not previously identified in congressional notification 13-67.
By Luhai Wong from Singapore, Singapore (_MG_7099) [CC BY-SA 2.0], via Wikimedia Commons
The additional items include 50 Joint Helmet-Mounted Cueing System and 90 AN/APX-126 Advanced Identification Friend or Foe Interrogator/Transponders.
Source: Alert 5