The US has begun directly providing weapons to Kurdish forces who have started to make gains against Islamic State (IS) militants in northern Iraq, senior officials say.

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 IS militants in recent weeks.

The US officials wouldn’t say which 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 officials spoke on condition of anonymity because they were not authorized to discuss the operation publicly.

The move to directly aid the Kurds underscores the level of US concern about the IS 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 US has begun directly providing weapons to Kurdish forces in northern Iraq

At the same time, the administration is watching carefully as a political crisis brews in Baghdad, and Secretary of State John Kerry warned Iraq’s PM 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,” John Kerry said.

“And our hope is that Mr. Maliki will not stir those waters.”

Speaking in Australia on Monday, John 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 Nouri al-Maliki.

Nouri al-Maliki is resisting calls to step down and says he’ll file a complaint against the president for not naming him prime minister.

John Kerry noted that Nouri al-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.

Nouri al-Maliki has accused Fouad 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.