The document is taking into account the geo strategic environment (Syria, Hezbollah and others):
Option 1: conventional air strike and its implications
Option 2: a tactical nuclear attack
Iran will activate Hezbollah in the north and Hamas in the south
How will the Americans react?
And all this pretty soon…
Source: http://csis.org/files/publication/100323_Options_todealwith_Iran.pdf
President Obama will not help Israel. He is no ally. I wish things were different, but you are on your own. I am worried that he will actually take the other side, but this may be going just a bit too far.