Smiling is good for health. It is the sign of a healthy and happy mind and is an indicator of friendly behaviour. And if you work at an airport, you are pretty much needed to do so. It’s just polite.

BBC

Unless you are the security force at Indian airports. Then you must not smile as much as you do or you’re giving a perception of lax security, leading to terrorist attacks.

Google Plus

Yup. That’s what the Central Industrial Security Force (in charge of India’s aviation security) said. 

Jetss

The CISF wants its staff to smile less so that it looks, ‘more vigilant than friendly’, according to the BBC

Rediff

CISF DG Rajesh Ranjan spoke to the Indian Express on the matter. 

We cannot be over-friendly with the passengers because one of the reasons cited as to why 9/11 happened… was excessive reliance on passenger-friendly features where security personnel went out of the way to ensure that the passenger is facilitated, thereby compromising on security.The staff has been instructed to go from a “Broad Smile System” to “Sufficient Smile System” to focus on ensuring foolproof security. 

Gifer

We are not ones to comment on what makes airport security better but asking the staff to smile less does seem a bit peculiar.