When is a landmine not a landmine? This is the question facing officials at the Pentagon who are due to decide whether to start producing a new generation of what the army calls "intelligent munitions" at the start of December.

While traditional landmines maim and kill indiscriminately, these weapons have to be monitored and activated remotely by a soldier watching events on a laptop. "If there's a school bus, the bus drives on, but if it's an armoured personnel carrier it will be destroyed," a US military spokesman says.

The mines will be designed to self-destruct without injuring anyone after a set period of time, which officials say will remove the threat to civilians after a war has ended.

The first system, called Matrix, was sent to Iraq earlier this year and relies on an operator using radio signals to detonate traditional claymore mines.

A more advanced system called Spider, ...