From personal expereice, profiling of international visitors to the USA won’t stop terrorists. Subjecting people who are suspected to be possibly like terrorists to additional searches and scrutiny, has come under a lot of fire for it’s negative “Racism” attributes, but proponents of profiling say it will increase security. Nope.
I ran the community of an online game for a few months. One day I decided to have player ranking, so I took the numbers and worked out a formula that put the good players on the top, and the bad ones on the bottom. Now if I had kept that list totally secret, and showed it to no one, it would have continued to give correct results, but when it was posted on the website, people began working to get up it. Bad players, started figuring out ways to beat the system, and began looking - on the stats - just like good players.
It’s the same way with any active form of profiling. Not all humans are idiots. As soon as bad people see that a twenty eight year old arab male is subject to extra hassles, they will send in sixty nine year old white females.