If more terrorists are on the way, WHY hasn't the wall been built?

Today's news says Al Queda openly admits it plans to attack the US soon, facilitated by inserting more operatives into this country. Why is the barn door still open? There's a snake in the yard and some fool won't shut the door! A second benefit would be to cut off the illegals traipsing across the border. So, now we have TWO very GOOD reasons to build the wall and patrol it.Three, if you count drug trafficing. Why hasn't this been done yet? Instead, we increase the tracking down of immigrants and visitors who have visa issues. Brilliant! That's just laziness. If they have a visa, we have their name and address. The ones giving us the trouble HAVE no Visas! Who would give an Middle Easterner a Visa to go to pilot school? Instead he learns a few phrases of spainish and pes himself off as a mexican illegal to get in. Closing the door will stop them both. There need be no 'racial profiling'.