IMO multiple interceptor launches, say 8 staged a few seconds apart, would statistically increase the chance of a kill.
Of course the biggest variable in that strategy would be the possibility of secondary launches from the attacking country. Some interceptors would have to be kept in reserve for that possibility.
All in all, the president should have been much better informed of his retaliation options than portrayed in the movie. It appeared to be the first time he was aware of them.
The female FEMA coordinator for the Chicago area was a bitch in general also unaware of basic protocols for such a situation.
On the plus side, I felt a lot of empathy for the army troops when they realized the intercept had failed.
Not sure if my math is correct, but this is my first stab at calculating the theoretical failure to intercept a missile with the launch of 8 interceptors.
(1.00 - 0.61)8 = 0.0005352009 = 0.05%
Which translates to a success rate of 99.95%
I just did that for fun. I do not claim to be Albert Einstein.