The Obama administration's announcement last week that it was pushing ahead with plans to build a multibillion-dollar 'virtual fence' along the U.S. border with Mexico is an important step toward immigration reform.

Securing the border is a necessary precursor, both politically and practically, to an overhaul of this country's failed immigration policies.

There will be no enforceable system without a border sealed to illegal entry, or at the very least some semblance of control.

The problem is that the virtual fence technology - a network of cameras, radar and communication gear - has a long way to go before it is a reliable, cost-efficient tool.