For a force that has built its reputation on an aura of momentum and invincibility, the Islamic State group is now dealing with a series of military setbacks in Iraq and a prolonged stalemate in the small Syrian border town of Kobani.

Gone are the days when IS was able to seize territory in both countries with relative ease. Its newfound problems, including a loss of oil revenue, raise questions about the extent to which it will be able to continue recruiting fighters who want to be with a winner.

"ISIS has run a very effective psychological campaign to intimidate its rivals and attract support and recruits," said Faysal Itani, a resident fellow at the Atlantic Council, using an acronym for the extremists. But now, he said, the need to maintain its reputation is limiting the group's options.

This is particularly true in Kobani, where a pre-emptive IS withdrawal in the face of U.S.-led bombings from the sky and ethnic Kurdish fighters on the ground could prove too costly.

"They have invested a lot in this battle, and people are noticing. They will soon start asking what's going on?" said Ayed, a Turkey-based Syrian activist who travels back and forth to the group's stronghold in the Syrian city of Raqqa. He declined to give his full name.

The prolonged fighting in Kobani is also distracting IS from more strategically important areas in Syria and Iraq where the militant extremists are already stretched on multiple fronts.

Nearly two months after IS launched its lightning assault on the Kurdish-dominated town near Turkish border, the group is bogged down in an increasingly entrenched and costly battle.

Syrian and Kurdish activists estimate nearly 600 Islamic State fighters have been killed — its heaviest losses since taking over large parts of Syria and Iraq in a summer blitz.

Kurdish residents say the group appears to be struggling with personnel, bringing in inexperienced fighters and new recruits to reinforce the town. These include members of the IS police force known as Hisba, reassigned from nearby towns and cities, such as Raqqa and Manbij, under the group's control.

"Many Hisba members have left Raqqa in the past two weeks, telling people they were headed to Kobani," Ayed said. They are not fighters."

Kobani residents say recent U.S. airstrikes targeting IS in Kobani have inflicted heavy damage. "Their bodies are left for days rotting in the street without anyone picking them up," said Farhad Shami, a Kobani-based activist.

In a move that some observers interpreted as a sign of weakness, the Islamic State group recently released a video showing a captive British photojournalist "reporting" from a place identified as Kobani. In the video, he says the battle for Kobani "is coming to an end" and IS is "mopping up."

But despite seven weeks of fierce fighting and the reinforcements on both sides, fighting positions around Kobani remain much the same as they did several weeks ago, with IS controlling about 40 percent of the town, according to Syrian and Kurdish activists and observers.

IS has also recently suffered losses on several fronts in Iraq, where it is fighting government forces, peshmerga and Shiite militias aided by Iran and the Lebanese Hezbollah group.

Last week, Iraqi forces recaptured the town of Jurf al-Sakher. IS also lost Rabia, Mahmoudiyah and Zumar, a string of towns near the Syrian border, last month. Besieged Iraqi troops have also managed to maintain control of Iraq's largest oil refinery outside the town of Beiji north of Baghdad, despite numerous attempts by the Islamic State group to capture it.

The group's diminishing returns in Iraq partly reflects the fact that it already controls so much of the territory populated by minority Sunnis. It would have a much harder time conquering areas populated by Shiites.

But even in Sunni areas, IS is having to contend with dissent. Over the past few days, the group has massacred more than 200 Sunni tribesmen from the Al Bu Nimr tribe in what is likely to be revenge for the tribe's siding with Iraqi security forces. The killings, in which the militants lined up and shot the men, suggest IS fighters now view them as a threat.

The group's difficulties are striking considering the relative ease with which it seized other towns and cities in Iraq and Syria this past summer. In Iraq's second largest city, Mosul, Iraqi security forces quickly abandoned their positions and weapons in the face of the marauding militants, melting away quickly in humiliating defeat.

Most other towns in northern and western Iraq saw a widespread disintegration of the security forces, mostly because of the Islamic State group's reputation alone in addition to grievances among the Sunni population that the militants were able to exploit.

In Syria, the group was able to capitalize on the chaos of the civil war to seize towns and villages abandoned by the government, routing out rival fighters in quick succession.

By the time it got to Kobani in mid-September, IS was stretched on multiple fronts. Riding on the momentum, however, it captured dozens of Kurdish villages and a third of the town in lightning advances that sent waves of civilians fleeing across the border into Turkey. Expectations were that the town would fall to the militants within days.

But unlike in Iraq where the militants already had a substantial, years-long presence, the IS fighters in Kobani found themselves in an alien environment and unfamiliar terrain, fighting against highly motivated and surprisingly resilient Kurdish fighters, according to Syria observers as well as Syrian and Kurdish activists.

"The Iraqi army was a severely demoralized force that didn't see a purpose in fighting for a central government whose credibility they questioned," said Shashank Joshi, a senior research fellow at Royal United Services Institute, a British think tank.

The Kurds, on the other hand, "are fighting a truly existential battle," he said.

A group of 150 Iraqi Kurdish forces known as peshmerga deployed last week to Kobani with more advanced weapons including anti-tank missiles and artillery to help bolster their Syrian brethren defending the town. They have provided artillery cover for fellow Kurdish fighters, but it is too early to say whether this has already made any difference on the ground.

Bayan Jabr, an Iraqi cabinet minister, said IS was simply fighting too many battles. He predicted a Sunni uprising in Anbar province following the massacres targeting the Al Bu Nimr tribe.

"I think Daesh is starting to fade," he said, using the Arab acronym for the group.

___

Associated Press writer Vivian Salama contributed to this report from Irbil, Iraq.