Attacks have been averted in US post 9/11, not because of PATROIT. Its because of the stringent measures taken, massive survielance, immigration facilities beefed up, foreigners accounted and tracked.
1. Here in India the borders are porous. The para-military at borders in India is most corrupt. 2. Here in India anyone can make a Ration-Card. The single most important doument to prove domicile. 3. Why no id-cards are issued and people tracked. As in Singapore. Everybody has i-card. No i-card no citizenship.
There are many many measures that can be taken to PREVENT and AVOID such acts leading to terror.
POTA is not a deterance, but a Salvaging measure, to digress attention from the main causes.