With at least $10 billion ($40 billion by some estimates) in drug money pouring in from the US every year, the Mexican cartels are flushed with cash and weapons, and are becoming more violent on a daily basis.

The conflict has become increasingly brutal, with victims beheaded and bodies dissolved in vats of acid.

By some estimates the cartels - which are fighting each other and the government at the same time – have 100,000 foot soldiers, compared to the Mexican army's 230,000.

Officials in Washington say the crisis has become a full-blown national security concern for the US, which for decades could count on quiet borders.

The US has stepped up its military assistance, but experts say there is no military solution, as long as demand for drugs in the US grows.

Riz Khan speaks with Asa Hutchinson, a former US Drug Enforcement Administration director and first under secretary of Homeland Security, about the growing concerns on both sides of the border.

Part 1