Mexico's inability to fully seal up border tunnels dug by drug smugglers poses a security risk and is an "open invitation" for cartels to carve out new tunnels, according to officials in the United States. On the U.S. side, drug tunnels have been filled with concrete since 2007, after the Los Angeles Times reported that they were being left unfilled because of budget constraints within Customs and Border Protection. Traffickers have reactivated or tried to reactivate at least four other tunnels in recent years, most recently last month near Tijuana's airport. Since 2007, it has cost Customs and Border Protection $8.7 million to fill drug tunnels, according to a 2016 report by the Department of Homeland Security. An estimated 20 large tunnels, constructed before and after 2007, are largely intact on the Mexican side, officials told the newspaper.

Source: Fox News January 16, 2017 02:58 UTC