It's a growing national security threat. Border tunnels that connect the bad guys on both sides of the U.S. Mexico border.
Our cameras got a a unique opportunity to go behind the scenes for a "Day in the Life" of the Border Tunnel Patrol.
Immigration Customs Enforcement (ICE), Border Patrol and the Drug Enforcement Administration use robots and radar to detect the cross border tunnels, which are a haven for human and drug smuggling.
ICE officials say cooperation with both sides of the border is essential.
"To really stop this threat of tunneling activity," said Tim Durst, Assistant Special Agent, ICE, "We need cooperation of the government of Mexico."
In the past several years, the number of border tunnels has increased 63-percent and the Department of Homeland Security says Mexico's President Felipe Calderon has pledged his support to crack down on this criminal activity.