Benoit Gomis has written a piece for World Politics Review on why a travel ban to terrorism hotspots (already in place in Australia, and recently proposed by Stephen Harper) is, at best, likely to be ineffective, and, at worst, counterproductive.

See the full article here: http://www.worldpoliticsreview.com/articles/16543/travel-bans-to-terrorism-hot-spots-won-t-deter-foreign-fighters