US soldiers are firing so many bullets in Iraq and elsewhere that the army's main supplier cannot keep up with the huge demand, US military officials say.
The bullet demand is the highest since the Vietnam, the army says
They say the army needs two billion bullets a year, but its government-owned supplier, Alliant Techsystems, can only make 1.2 billion.
To fill the gap, a US firm and Israel's state-owned bullet-maker were awarded contracts for 70 million rounds each.
But they will still be some 300 million rounds short, army officials say.
Working around the clock
"We're at war," was how US Army spokesman Major Gary Tallman explained the reason for the dramatic increase in the demand for small-calibre ammunition to the Philadelphia Inquirer newspaper.
The US military say that - with almost daily firefights in Iraq and also ongoing operations in Afghanistan and elsewhere - the demand is higher than at any time since the war in Vietnam.
They say US non-combatant troops in Iraq are also using more bullets in training, due to an increased number of attacks by insurgents on supply and transportation units.
Alliant Techsystems chief executive Dan Murphy told the Associated Press news agency that the company had gone through its fastest increase in production of bullets - 37% in the first three months of the year - to meet the demand.
He said some production lines at the firm's plant in Missouri were operating around the clock.
The army said it expected the Winchester Ammunition of East Alton, Illinois, and also Israel Military Industries Ltd of Israel to start delivering bullets on their new contracts next month.