US Invasions

Working on a bit more philosophy, why it so quiet around here at the moment:
 
For each of the following arguments:
(1) standardise the argument;
(2) state the necessary and sufficient conditions of any conditional statements; and
(3)
judge whether the argument is valid or invalid.
 

(xvii) If America launches an attack, it is inevitable that innocent people will die. But the US is now in a position where if it does not launch an attack, it will be seen to have given in to the terrorists. They cannot allow themselves to be seen in that light, because if they were understood to have surrendered to these terrorists, then that would encourage more such attacks. We do not want to live in a world where such attacks become accepted. We must, therefore, resign ourselves to the fact that there will be innocent victims.

1.2: If the US does not launch an attack, it will be seen to have given in to the terrorists.
1.1.1: If the US was understood to have surrendered to these terrorists, then that would encourage more such attacks.
1.1.2: We do not want to live in a world where terrorist attacks become accepted [i.e. we do not want to encourage more attacks]
1.1: America cannot allow itself to be seen in that light [of giving in to terrorists]
1: America must launch an attack [implied]
2: If America launches an attack, it is inevitable that innocent people will die.
C: There will be innocent victims.

1.1.1: The US not launching an attack is the sufficient condition, giving in to the terrorists is the necessary condition.
1.1.2: The US being understood to have surrendered to these terrorists is the sufficient condition, encouraging more such attacks is the necessary condition.
2: America launching an attack is the sufficient condition, the inevitability of innocent people dying is the necessary condition.

1.1.2 denies the necessary condition of 1.1.1, which leads to the sub-conclusion of 1.1. 1.1 denies the necessary condition of 1.2, which leads to the sub-conclusion of 1. 1 affirms the sufficient condition of 2. Therefore the argument valid.
 
I checked it against the staff answer, and it is all correct.  How about that?  The argument being valid, by the way, does not mean I agree with it.  What this does is help us determine first whether the argument is valid or not, and if it is, the legitimate ways of countering (or supporting) the argument.  For instance, in this case, sub-premise 1.2 looks vulnerable.