Is the oil crash a secret US war on Russia?

Lower oil prices, reflected in falling petrol prices at the pump, have been a boon for Western consumers. Are they also a potent US weapon against Russia and Iran?

That's the conclusion drawn by New York Times columnist Thomas L Friedman, who says the US and Saudi Arabia, whether by accident or design, could be pumping Russia and Iran to brink of economic collapse.

Despite turmoil in many of the world's oil-producing countries - Libya, Iraq, Nigeria and Syria - prices are hitting lows not seen in years, Friedman writes.