Shortly after 9/11 there was a call for aliens from other countries to report and register. Included in that group who reported were 13,000 Pakistanis who were illegal. Not included was a massive wave of illegal Pakistanis and others who fled to Canada.
There were many others-including several thousand living in Midwood, Bklyn., a neighborhood I'm intimately familiar with-that simply returned to Pakistan.
So you see, when we want to do something about aliens we sure as hell can.