Even if there weren't any planned attacks at the moment, the preventive and protective actions are usually done regardless of the temporary costs.

Without going much political, I can say that move was one of the most critical ones, maybe right after preventing nuclear warfare, because I don't want to think how much worse the American retaliation in the last 20 years would be if there was even one more kamikaze plane, especially considering that we now measure warcrimes in magnitudes of 9/11.