Rach3 said:
Why terrorists prefer to enter the country by way of desert borders, and why they face greater hardship by other means like temporary visas
It is indeed a very rare scenario, but if there's an individual that cannot risk capture by the authorities it would be a reasonable route. Why such an individual would want to enter the states is beyond me.
Rach3 said:
-How chickenmesh would solve everything
-Why desperate smugglers in 130mph speeding vehicles won't defeat everything
Modern barriers are far from chickenmesh. They involve quite a wide and deep tunnel all across the planned barriers to house cabling, filled with concrete that serves as a steady base to the poles. There are several options for what's on top, that include placing modular pre-cast concrete wedges that can be piled into any given size; placing pre-cast reinforced concrete defense posts with an optional living area; erecting an indicative fence with an optional vehicle barrier, not unlike highway barriers. The latter option is the most economical. The fence is composed of dozens of trigger wires with rather sensitive sensors (in windy conditions there are sometimes false alerts, but those are usually discernible as the operator is indicated the geometry and characteristics of the disturbance), positioned in several layers, each with its unique characteristic relevant to its height. At the top is an ultra-sensitive trigger wire. The aforementioned soft sand strip allows a patrol to arrive at the spot and examine for penetration, when staffed with a good tracker it is the most accurate tool.
This can be complemented by other observation devices such as tactical radars and vehicle-mounted intelligence units. When placed correctly, they are highly effective though they require more personnel and maintainance.
Rach3 said:
-How, technically, unmanned aerial vehicles would solve everything (in combination with chickenmesh)
That depends on what you call everything. These barriers are of quite limited effectiveness in certain conditions that I would rather not discuss. However, if I was to decide how to close the Mexican border to illegal immigrants (and terrorists?) in the most cost-effective way I would choose an array of an indicative fence with a vehicle barrier, stationary cameras where they would be efficient, and UAVs for the largest and least active sections.
Rach3 said:
-How the agencies could effectively monitor ten thousand cameras and back them up with paramilitary support
The cameras relay their feeds by cabling and radio signals to a command center. From my very limited experience with Americans, it would probably be constructed NORAD-style with lots of cubicles manned by operators organised into a single large unit. Each operator can operate any given number of cameras, thanks to modern variable sensitivity motion detection systems that alert the operator when certain disturbances are picked up by one of its cameras. Individual posts will probably interface with a central system to which the operator can input data, and have it put on a really big screen (generals love big screens). The command center will be linked to the ground forces by simple radio relays. These forces can be spread out in small bases at the rear of the tactical depth, where the off-duty force will serve as a reserve that can intercept anyone outrunning the patrol on-duty.
Rach3 said:
-Where is there historical precedent where similar methodologies were effective and beneficial (Berlin Wall doesn't count!)
Both the barrier around the Gaza Strip and the controversial separation barrier have proved very effective in stopping infiltrations. I do not intend to enter a discussion about their moral value, but they are certainly extremely valuable in an operational perspective. There have been ways of circumventing certain elements of the barriers but it takes so much work to avoid being identified as you're crossing the physical barrier, it's statistically impossible that you won't be picked up by an observation device. Again, additional elements can be used to concentrate an effort on a particular section that is problematic, effectively sealing it (of course, someone can always f*ck their job up).
Rach3 said:
-Why tunnels won't defeat everything
Again, that depends on how big a buffer zone you have and where you place complementing resources. Tunnels are a possibility, but one that severely limits the infiltrators. Use the tunnel too much, and someone will find out - so the smugglers/infiltrators have to work really hard to dig it, and then be patient and overcome their greed and self-confidence and use the tunnel conservatively - which they normally don't. So it's a possibility, but a rare one.
Rach3 said:
-Why ladders won't defeat everything
A ladder enables to cross the barrier quite quickly. However, if it is a brute method the fence will indicate it. If it is a custom-constructed ladder to enable crossing the fence without triggering it, it will be impossible to carry it across the fence, increasing the chance of discovery by other means.