Tunnels into Egypt

Smuggling tunnels between Egypt's Sinai Peninsula and the Gaza Strip have for years been a way around the Israeli blockade of that Palestinian territory.  Now, however, they are a potential conduit for support for armed Islamists in the Sinai, and as a result, the Egyptian military is cracking down:

Starting with the August 2012 massacre of 16 Egyptian soldiers in Sinai, Egypt’s national security establishment realized that the flow of weapons and fighters can travel in both directions. Since June 2013, in the lead up to President Mohamed Morsi’s ouster in Cairo, the Egyptian military has maintained its most effective operation yet against the tunnel network...

In the first week of July, when the military removed Morsi from power, OCHA estimated that fewer than ten tunnels were operational. By the end of August, Raed Fattouh, president of the Palestinian Authority’s coordination committee for the entry of goods to Gaza, said that Gaza’s tunnels were only functioning at 30 percent of their capacity. Even with this slight easing, the tunnels have yet to return to their post-Mubarak traffic.

The post-Morsi counter-tunnel operations have also been the most sustained effort to date. Estimates of the number of operational tunnels in June 2013, before the latest crackdown, range from below 100 to as many as 220 or even around 300. By late September only around ten were open. According to another report, fuel was still being smuggled through the open tunnels—at less than half the rate as during early 2013—but exclusively for the use of Gaza's power station. In late September, the spokesman of the Egyptian armed forces said Egypt had destroyed the effectiveness of the tunnel network. The Egyptian military also announced that it would establish a “buffer zone” along the Sinai border.

A crackdown on those tunnels could also weaken Hamas, which relies on its control of those routes for goods and services to exercise control over the goods and services themselves.  I suspect Egypt's generals regard that as a useful side benefit.