If we had had such monitoring pre 9/11 there a great chance the tragedy would never have occurred.
After the fact, it turned out that we had a great deal of information about the 9/11 attackers. That didn't stop that attack.
Or the Cole attack, where we also (after the fact) found that we had information, or the Boston attack, where the new 'capture every text message' monitoring was in place.
It isn't working. Americans are still dying.
The down side is that Americans are also losing their freedom and privacy.
And still we die, even with the monitoring.
So find another solution.
/johnny