Kurdish Peshmerga forces raise the Kurdish flag at a checkpoint on the road leading from Kirkuk to northern Iraqi city of Tikrit on June 30, 2014. (Marwan Ibrahim/AFP/Getty Images)

Each day, Kurdish security forces­ in northern Iraq skirmish with fearsomely armed Islamic State militants along their new, nearly 650-mile border. The Kurds have held their own so far. But without new arms supplies or financial assistance, their fight is unsustainable, a senior Kurdish official said.

Masrour Barzani, the Kurdistan Regional Government’s intelligence and security chief, described his forces as “overstretched.” In an interview this week, he called on the United States to provide direct military assistance to his semi­autonomous region, which he said has been left to fight the extremists unaided.

For the Kurds, the Islamic State’s blitz across northern Iraq in recent weeks has in some respects been a boon. Iraqi military forces­ rapidly withdrew from the north, enabling the Kurds to seize areas where they had disputed control with Baghdad, including the oil-rich city of Kirkuk.

But the expanded borders mean more land to protect from their new, unwelcome neighbors. That added burden comes as the Kurdish region’s relations with Baghdad are sharply deteriorating, with the central government withholding funds, banning cargo flights and making it difficult for the Kurds to replenish their arms.

“It’s a big responsibility, it’s a long border, many of our troops are there and we don’t know how long the situation will continue,” Barzani said. “We are really overstretched.”

Relations with Baghdad have soured as the Kurds have pushed toward independence and have begun to sell crude oil independently of the national government.

The Kurds are supposed to receive a share of U.S.-supplied weapons to Iraq, but they have gotten “not a single bullet,” Barzani said. Meanwhile, Islamic State fighters have seized weapons worth hundreds of millions of dollars from retreating Iraqi soldiers.

“This is the truth that the world should know,” he said. “So we are left out to fight all these terrorists, all these problems on our own.”

Some of the about 750 American troops sent to Iraq recently to protect U.S. facilities and serve as military advisers have been dispatched to the Kurdish region, but they are so far taking on only an assessment role, according to Barzani. He declined to comment on reports that a U.S. drone base has been established on Kurdish territory.

“We hope that their assessments are going to be helpful to let Washington know how serious the situation is and how big of a need we have for military support,” Barzani added.

The Iraqi government has opposed efforts by the Kurds to acquire weapons, saying such sales are illegal, with only the central Defense and Interior ministries authorized to buy arms. But the Kurds have long pursued secret deals to replenish their stocks.

Recently, though, the central government, which controls Irbil’s airspace, has banned cargo flights to the north, which in the past have brought in new weapons from Eastern Europe.

The squeeze is being felt on the front lines. One Kurdish commander said that security forces were under new orders not to fire on the enemy unless attacked or until their opponents were within 20 meters — about 65 feet — to save on ammunition. He said the mandate, issued in lateJune, meant that after one bout of fighting, Islamic State militants were able to retrieve bodies and damaged vehicles.

“I could see 20 dead bodies, very short range from us, but we had orders just to let them take the stuff, and hold fire,” Lt. Col. Kamaran Hourami said.

“We need newer and better weapons,” he said.

Barzani said that the Kurds had procured some “small to medium” arms but that when most allies are approached, the feedback is “not positive.”

‘We’ve had conversations’

With Washington wary that Iraq’s main security forces­ are being infiltrated by Shiite militias, the more stable Kurdish north makes a logical partner for the U.S. government in trying to curb the Islamic State, Iraqi and Western analysts say. But U.S. officials are reluctant to undermine Baghdad’s authority, they added.

In Washington, Brett McGurk, the Obama administration’s diplomatic point man on Iraq, told lawmakers Wednesday that “we’ve had conversations” with Kurdish leaders “about how we can work with them on their future.” But McGurk, the deputy assistant secretary of state for the Near East, made clear that the administration believes that “the best way to go” is for the Kurdish region to

stay inside Iraq’s “constitutional framework.”

“I think the heart of every Kurd wants an independent state,” McGurk told the House Foreign Affairs Committee. “I think we have to recognize that.”

McGurk did not directly address Kurdish appeals for U.S. weapons. But he made clear that the administration does not support independent Kurdish oil exports outside the central government framework. “We have an obligation to say when people ask that there is a legal risk for taking oil without an agreement” with Baghdad, he said.

The Kurdish region is meant to receive 17 percent of the national budget after certain expenses are deducted, but Baghdad has refused to pay until the Kurds cease attempts to unilaterally sell oil.

The economic situation “couldn’t be worse,” said Dlawer Ala’Aldeen, president of the Irbil-based Middle East Research Institute. “The Ministry of Finance is actively seeking ways to borrow money. People’s salaries need to be paid; refugees need to be provided for.”

The Kurdish security forces, known as the pesh merga, have not been paid for months.

In Washington, McGurk acknowledged that Iraqi politics had prevented an oil agreement that would allow Kurdish exports. But he said that the budget being considered by the Iraqi parliament includes a fair share for the Kurds and that the administration has pressed Baghdad to pay the Kurdish region what it is due.

Barzani said “tens” of Kurdish fighters have been killed in the conflict, but he declined to provide a number. One of them was Talat Hussein Aziz, a 31-year-old pesh merga fighter who was fatally shot when the Islamic State launched an assault on his base last month.He left behind a wife and two young daughters.

But even amid the hardship, there seems to be little in the way of complaint among fighters. “Of course, we are under a lot of pressure,” said Yawar Hussein Aziz, Talat’s 24-year-old brother, also a pesh merga fighter. Pesh merga roughly translates as “those who face death.”

“I feel it among my friends, but they wouldn’t even think about not defending their country,” he said.

“We chose this way. We might die, but it’s a point of pride to shed blood for Kurdistan.”

Karen DeYoung in Washington contributed to this report.