Smoke counters are most often used to obscure movement from enemy forces. At the beginning of each game, roll a d3. This is the number of smoke counters each side is able to deploy during the course of a game.
To deploy smoke – an infantry unit will need to sacrifice an activation to pop smoke. During their activation place a 6 inch smoke marker anywhere within 6” of the unit and in any direction. Any fire that draws line of sight through the smoke screen will receive an -1 modifier to their fire action. This does not affect flying vehicles or artillery.
The smoke screen will last for the duration of your turn and your opponent’s turn. After that, remove the smoke from play.
Note – a lot of modern tanks have smoke generators but many do not. In these cases I would say that if smoke canisters are modeled on the vehicle go ahead and allow it…