In what could rank as one of the worst use of resources of all time, an expensive Patriot missile has been used to shoot down a humble drone.

The quadcopter drone was worth US$200 ($280) and the missile US$3 million ($4.2m). Patriot defence missiles are radar-targeted weapons usually intended to down enemy aircraft and ballistic missiles.

According to news reports, US general David Perkins revealed the Goliath-smashing-David-event a military symposium.

The strike was made by a US ally, he said.


"That quadcopter that cost 200 bucks from did not stand a chance against a Patriot," he said, according to the BBC. "Now, that worked, they got it, OK, and we love Patriot missiles."

Perkins pointed out the obvious - that deploying large surface-to-air missiles as a defence was not good bang for your buck.

"I'm not sure that's a good economic exchange ratio," he told the Association of the United States Army's Global Force symposium in Alabama, the US.

"In fact, if I'm the enemy, I'm thinking, 'Hey, I'm just gonna get on eBay and buy as many of these $300 quadcopters as I can and expend all the Patriot missiles out there'."

No further details were given, but Perkins said it involved "a very close ally".

"It is clearly enormous overkill," Justin Bronk, a researcher at the Royal United Services Institute, told the BBC.

"It certainly exposes in very stark terms the challenge which militaries face in attempting to deal with the adaptation of cheap and readily available civilian technology with extremely expensive, high-end hardware designed for state-on-state warfare."