Solution to areas incompatible with continuous hard barrier construction, ie. "environmental concerns" animal migration etc.
Construct a series of two story concrete block houses.
Climate controlled living/cooking/showers upstairs, 5 bay garage, shop and holding cells downstairs.
Construct a paved covered carport along the back (away from the border) with four ready ATVs equipped with a mounted M249.
All agents staffing the blockhouses are issued M4s and Glock 21s.
On the (flat) roof of the building have continuous observation and defensive positions around all sides.
A 30 foot tower on top of each blockhouse for HD, FLIR cameras, communications and cell antennas.
HD optical zoom cameras controlled and connected to PCs in the living quarters running motion detecting software.
FLIR cameras are likewise controlled and connected to displays on large screens for constant observation.
Have vibration and magnetic detection sensors distributed to the front and between each blockhouse that will alert the detection position in the controlling PCs.
Link all blockhouses with TSOA, TIGR or SUDA like data sharing so any single blockhouse outage will not affect the links with the other blockhouses across the border.
Construct one blockhouse every half mile in all areas "incompatible" with hard barrier construction along the border.
If a particular area becomes overwhelmed with too many crossing attempts, begin hard barrier construction between the blockhouses. Open areas are only allowed directly next to the blockhouse and they can be closed off with barrier gates if needed.
Continue the hard barrier construction between the blockhouses until the problem area is under control.
This system will allow total control of the border as there will be no location further than 1/4 mile from a blockhouse.
Rotating shifts could cut back on how many personnel would be needed and in periods of low activity there might only be one or two Agents in every other blockhouse.
This concept would only be necessary when there is a REAL hazard presented to the environment, endangered species and air / water quality, whatever, by the presence of a contagious wall or 2 3 layer fence.
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Air drop tens of millions of leaflets stating that there will be unannounced nuclear demolitions occurring iminently.