What does "threat" do in The Division?

I'm currently trying to figure out a good tank build for challenging dailys and came across the threat property that silencers and certain muzzle breaks have.

Threat is also mentioned in the character sheet.

Examples of items with the threat property

(almost?) all silencers reduce the threat by X%
some muzzle breaks increase threat by X%
loud vent muzzles always increase threat by X%

Theories I have

Threat lets enemies flee

A higher threat level would drive the enemies away from you but then I wonder why I would want to reduce the threat as a sniper for example

Threat increases "aggro"

Another theory I have is that threat increases your aggro level and enemies will choose their target based on the highest threat. Then it would actually make sense to decrease your aggro level as a sniper / glass canon.