According to Defense News, Singapore's Apache fleet is being upgraded with a new satellite communications system, believed to be IAI/ELTA's EL/K-1891 Ku-band network, and an integrated electronic warfare system, which was previously identified as being from Elbit Systems.
In August 2017, Defense News reported that Singapore’s fleet of Boeing AH-64 Apache attack helicopters and CH-47 Chinook heavy-lift helicopters were fitted with defensive suites from Elbit Systems as part of survivability and mission capability upgrades.
Back then, Singapore’s Ministry of Defense said that the "upgrading program involves equipping the AH-64D with a Helicopter Integrated Electronic Warfare System (HIEWS) to enhance survivability and SATCOM for more robust communications."
The recent Defense News report also reveals that Singapore is using its Apache helicopters in an air defense role against a wide spectrum of aerial threats, including light aircraft or UAVs. The recent interception of an Iranian UAV by an Israeli Apache raises the question of whether Israel is also sharing particular combat doctrines with the Singaporeans.