Walls and Strategic Innovation in Violent Conflict
- Matthew Nanes,
- Trevor Bachus
Abstract
Governments build walls to curtail a range of illicit activities like
immigration, crime, and terrorism. What impact do walls have on the
characteristics of illicit activity? We argue that while physical
barriers can effectively prevent a narrow category of unwanted behavior,
they induce actors to respond strategically and develop new tactics,
changing the nature of illicit activity and leading to new threats. We
test this argument in the context of Israel's security barrier built to
reduce terror attacks. Using an instrumental variable unrelated to the
underlying threat of attack, we analyze
short-term changes in the barrier's porousness. We ?find that terror
attacks in Israel are indeed less likely when the barrier is more
secure. However, we also observe evidence of
displacement. Attacks and fatalities are most likely immediately after
the government eases temporary restrictions on movement, suggesting that
previously-planned attacks were delayed, not prevented. Furthermore,
when the barrier is more secure, terrorists substitute weapons that are
less affected by the barrier, and carry out attacks in systematically
different locations. Ultimately, walls' impacts on any challenge depend
not just on how well they prevent movement but also on illicit actors'
strategic responses.