I have some questions that look "simple" at first sight but where I was unable to give an answer :

- When do I have to announce that I want a unit to be placed in KZ / QZ / BZ? (When I play my unit? When I solve the action of playing my unit?)

- When a unit enter play?

Some questions come to me when I saw the rule book and read that a unit is placed when it is played... (which correspond to the time you pay the cost of your unit card). (p. 10 / 11, bottom of the page)

From my understanding it's:

-You pay the cost of the unit/support and reveal the card

...Your opponent may respond

-You announce where you will place the unit/support (KZ/QZ/or BZ or even the capitol itself it's a legend) but it's not there yet, it's still in transition from your hand to the field.

...Your opponent may respond

-The card enters play

....Your opponent may respond.

I placed the "opponent may respond" sections just because it seems like these would be the breaks in each step of playing a card in which an opponent could respond to each event occuring.

Lukas gave me the answer :

Thanks for the question. You declare the zone that you are playing the unit into when you attempt to play it from your hand, however the unit does not enter the zone until it enters play. So first you pay the cost and declare the zone, then when the action chain resolves the unit will enter play in that zone.

As I was saying something simple but that I was not really able to get with certitude from the rules book.