Can nuclear war be triggered before the end of game? The reason I ask is that the rules seem to indicate that you only check for nuclear war when doing scoring. But lets say that you playing the game on the first few turns and get three or more battlegrounds with the same color DEFCON symbols in your sphere of influence. Do you trigger nuclear war the second you get three or more battlegrounds with the same color DEFCON symbols in your sphere of influence or is it only during scoring that nuclear war can be triggered?
On a side note, I was confused about this wording on page 8: "...if the two cards match their colour DEFCON symbol you immediately place your card in your own sphere of influence." My confusion is with respect to what cards this rule is talking about. Is it both cards in your own hand, or if a symbol color from one of the cards in your hand matches a symbol color of one of the cards in your opponent's hand?
Nuclear War is only triggered at the end when you do the scoring. To answer your question about matching DEFCON colors, it is talking about the final card each player has in his/her hand at the end. Each player has just one card at the end. If they match in DEFCON color, they are each played into their owner's sphere. This may cause Nuclear War.