The US is already doing something similar for potential terrorists - - they essentially handhold people they believe to have the potential to carry out a terrorist plot. This American Life had an episode called The Convert [1] and Rolling Stones had a similar article [2]
[1] http://www.thisamericanlife.org/radio-archives/episode/471/t...
[2] http://www.rollingstone.com/politics/blogs/national-affairs/...