Oil futures have surpassed the once unthinkable price of $120 a barrel.

Oil reached its latest milestone on a mix of threats to overseas crude oil supplies. A threat by Kurdish rebels in Iraq to attack American interests has investors concerned. And an attack on an oil facility in Nigeria cut oil supplies.

Meanwhile, defiant comments by Iranian leaders about the country's nuclear program raised worries about broader conflict in the Middle East.

Light, sweet crude for May delivery rose to a trading record of $120.21 a barrel on the New York Mercantile Exchange.

The falling dollar is also sending crude prices higher.