We thank Mr Loong Chik Tong for his letter (Security at airport's airside needs attention too; Nov 20).

Changi Airport has a multi-layered security system.

Using integrated security technology and processes, security personnel are deployed to meet different security challenges and scenarios at the airport, including the terminal buildings, airside and its perimeter.

As pointed out by Mr Loong, security threats may extend beyond the airport terminal buildings and public spaces to the airside areas.

Therefore, airside security is very important and we regularly review the security system to address the new challenges in this evolving security environment.

Alan Xavier Tan

Vice-President

Aerodrome Safety and Aviation Security

Changi Airport Group