A problem of that size, can't be solved by sheer force as in using cops to play cat and mouse with each one of them to put them on the next bus/flight repeat-and-rinse to infinity, it's not going to work, it can't work and it's going to cost everything you have, it's non sense ultimately. And I'm not just counting the new comers I also take the past decades into account when I say "a problem of that size" Ideally, you want them to not want to come in the first place, and for those who are already here you want them to leave on their own, you want them to run away as far and as fast as possible from your territory, that's what you want because that's the cheapest and most effective way to deal with the problem. If you're serious about dealing with the problem you want to get there. So, the idea, is to turn your territory into the literal valley of death for anyone who's not "welcome"; no resources to sustain life are available and the longer you stay the more your chances of dying increase. To render their stay impossible in every possible way to put in simply. And there are ways to achieve just that, it's not a technical problem. Problem is that all the practicable ways I can think of have a dystopian dimension.