One of many contingencies, b . . .
The Pentagon has clontingency plans for attacks from Russia, from Poland, from Canada, from Andora (movie tie-in: Peter Sellers' "The Mouse that Roared").
Without the signature, they mean nothing. With the signature, they mean little (movie tie-in: Eric Roberts' and Cheech Marin's "Rude Awakening").
It could happoen -- but likely not.
If so, Obama has less than 3 years to kick the whole thing off. Of course, I would never put it past Al-Qieda (The Camp) to do that for him.