WASHINGTON // The United States is facing the limits of air power in Kobani, where ISIL fighters are steadily closing in on Kurdish fighters despite a series of US bombing raids.

Fighter jets and drones from the world’s most powerful air force have carried out at least eight attacks over the past week near Kobani, but the raids have failed so far to turn the tide in the battle for the town near the Turkish border.

For some analysts and former US officials, the town’s plight illustrates how bombing from the air has serious limitations without troops to guide the strikes to a target or a well-organised ally who can take advantage of the air support.

The Kurdish defenders are far from a coherent army and are badly outgunned, said Seth Jones, a former adviser to US special operations forces.

“At this point, it looks like Kurdish fighters face a well-organised and well-funded [ISIL] force,” he said.

“This is a notable concern across Syria, where US air power is not being coordinated well with ground forces – in part since there are a plethora of rebel groups in Syria.”

The number of US strikes near Kobani has been limited, and on a smaller-scale compared to some other locations, which some experts say reflects a murky intelligence picture.

Without forward air controllers in Kobani, fighter pilots likely find it difficult to distinguish friend from foe, particularly as the ISIL militants seek to move among civilians to conceal their location, said Ben Connable, a retired US marine intelligence officer.

“We probably don’t have good enough intelligence to separate all the prospective targets from friendly fighters,” said Maj Connable, now a senior analyst at the RAND Corporation think tank.

Even with the advanced cameras and sensors on US planes, clearly identifying an enemy target remains difficult, and even more challenging in poor weather.

“It’s hard to tell,” Maj Connable said. “You may think you have identified something in a video, but you may not have.”

But Kurdish leaders and some critics in Washington have accused Barack Obama of taking an overly cautious approach, arguing that US airstrikes could stop ISIL fighters in their tracks if the full potential of American air power was unleashed.

Retired US air force lieutenant general David Deptula said the aircrews flying the combat missions are hampered by cumbersome procedures and restrictive approval rules for strikes that are undercutting the impact of the campaign.

“There is a sense and there is feedback that there are too many people trying to micromanage the application of air power,” said Gen Deptula, who oversaw air campaigns in Iraq and Afghanistan.

In Kobani, “there needs to be 24/7 constant overwatch, and every time there are ISIL troops, vehicles, weapons that are observed – they need to be hit immediately”, he said.

The elaborate approval process for strikes is a legacy of the war in Afghanistan, he said, where US forces took extra precautions after disastrous mistakes that left civilians killed.

But he said the war in Syria and Iraq is a much different situation, where the targets are troops in trucks moving down roads.

Pentagon chief Chuck Hagel has denied that the air campaign is being micromanaged by the president or his aides, and that the head of US Central Command, Gen Lloyd Austin, has full authority to wage an unfettered air war.

A senior defence official rejected any suggestion that the airstrikes were being held up by meddling from the White House or bureaucratic rules.

“The idea that the war is being conducted out of the White House is wrong. Gen Austin has all the authorities he needs,” said the official.

The Pentagon said on Friday that the airstrikes in Syria were not about altering the outcome of battles there but disrupting the ISIL’s supply lines to help offensives carried out by Iraqi forces next door.

“I just want to make sure that I stress again that the focus in Syria has really been about the sanctuary and safe haven they enjoy,” said Rear Adm John Kirby said.

“In Iraq, it’s really been much more focused on supporting Iraqi security forces and Kurdish forces on the ground.”

* Agence France-Presse