Previously, the US had insisted on only selling arms to the Iraqi government in Baghdad, but the Kurdish peshmerga fighters had been losing ground to Islamic State militants in recent weeks.
The officials wouldn't say which US agency is providing the arms or what weapons are being sent, but one official said it isn't the Pentagon. The CIA has historically done similar quiet arming operations.
The move to directly aid the Kurds underscores the level of US concern about the Islamic State militants' gains in the north, and reflects the persistent administration view that the Iraqis must take the necessary steps to solve their own security problems.
The additional assistance comes as Kurdish forces yesterday took back two towns from the Islamic insurgents, aided in part by US airstrikes in the region.
President Barack Obama authorized the airstrikes to protect US interests and personnel in the region, including at facilities in Irbil, as well as Yazidi refugees fleeing militants.
US Secretary of State John Kerry urged the people of Iraq to remain calm amid the political and military upheaval.
Speaking in Australia today, Kerry said there should be no use of force by political factions as Iraq struggles form a government.
He said the people of Iraq have made clear their desire for change and that the country's new president is acting appropriately despite claims of malfeasance by Prime Minister Nouri al-Maliki.
Maliki is resisting calls to step down and says he'll file a complaint against the president for not naming him prime minister.
Maliki has accused Massoum of violating the constitution because he has not yet named a prime minister from the country's largest parliamentary faction, missing yesterday deadline.
