The US previously insisted on selling arms only to the Iraqi government.
American officials say the administration is close to approving plans for the Pentagon to arm the Kurds.
Recently the US military has been helping facilitate weapons deliveries from the Iraqis to the Kurds, who had been losing ground to the Islamic State militant group, formerly known as Isis.
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.
A senior State Department official would only say that the Kurds are "getting arms from various sources. They are being rearmed".
To bolster that effort, the administration is also very close to approving plans for the Pentagon to arm the Kurds, a senior official said. In recent days, the US military has been helping facilitate weapons deliveries from the Iraqis to the Kurds, providing logistic assistance and transportation to the north.
The additional assistance comes as Kurdish forces on Sunday took back two towns from the Islamic insurgents, aided in part by US airstrikes in the region. President Barack Obama authorised the airstrikes to protect US interests and personnel in the region, including at facilities in Irbil, as well as Yazidi refugees fleeing militants.
US Defense Secretary Chuck Hagel said the airstrikes "have been very effective from all the reports that we've received on the ground".
He declined to detail how or when the US might expand its assistance to Iraq, or if military assessment teams currently in Baghdad would be moving to a more active role advising the Iraqi forces.
"We're going to continue to support the Iraqi security forces in every way that we can as they request assistance there," Mr Hagel said during a press conference with Australian Defence Minister David Johnston.
At the same time, the administration is watching carefully as a political crisis brews in Baghdad, and US Secretary of State John Kerry warned Iraq's embattled prime minister Nouri al-Maliki to maintain calm among the upheaval.
"We believe that the government formation process is critical in terms of sustaining the stability and calm in Iraq," Mr Kerry said. "And our hope is that Mr Maliki will not stir those waters."
Speaking in Australia, Mr 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 Mr Maliki.
Mr Maliki is resisting calls to step down and says he'll file a complaint against the president for not naming him prime minister.
Mr Kerry noted that Mr Maliki's Shia bloc has put forward three other candidates for the prime minister job and says the US stands with the new president, Fouad Massoum.
Mr Maliki has accused Mr Massoum of violating the constitution because he has not yet named a prime minister from the country's largest parliamentary faction, missing a Sunday deadline.
Mr Hagel and Mr Kerry are in Sydney for an annual meeting with Australian defence and diplomatic leaders.