Members of a Syrian armed group hold positions in the front line against the Islamic State outside Ain Issa, in the countryside of Raqqa province. (Alice Martins/For The Washington Post)

In this abandoned desert town on the front line of the war against the Islamic State in Raqqa, local fighters are fired up by announcements in Washington that the militants’ self-proclaimed capital is to be the next focus of the war.

But there is still no sign of the help the United States has delivered ostensibly for the use of the Arab groups fighting the Islamic State, nor is there any indication it will imminently arrive, calling into question whether there can be an offensive to capture Raqqa anytime soon.

Fifty tons of ammunition air­dropped by the U.S. military last week and intended for Arab groups has instead been claimed by the overall command of the Kurdish People’s Protection Units, or YPG, which is fighting alongside Arab units but overwhelmingly dominates their uneasy alliance, according to Kurdish and Arab commanders.

The question of whether Arab or Kurdish fighters get the weapons is crucial, in part because of Turkish sensitivities surrounding the United States’ burgeoning relationship with the Syrian Kurds. Turkey accuses the YPG of affiliation with the Kurdistan Workers’ Party, or PKK, designated a terrorist organization by Ankara and Washington, and has already lodged a complaint with the U.S. Embassy in Ankara that the YPG received the weapons intended for Arabs.

Just as significant, however, is the recognition that Kurds are unlikely to be able — or perhaps even willing — to fight for the Sunni Arab lands controlled by the Islamic State, including Raqqa, the jewel in the crown of the militants’ self-styled caliphate and a city the Kurds do not aspire to govern.

Ain Issa lies only 30 miles north of Raqqa, and half of that distance is empty desert, according to rebels with the Thuwar al-Raqqa, or Raqqa Revolutionaries, brigade, the only Arab group fighting alongside the Kurdish YPG in the town.

“We could reach it in 10 days,” said Abu Awad, who commands the brigade’s outpost on the front line, marked by an earthen barricade snaking through the desert. But his group is armed only with AK-47 rifles, a few rocket-propelled grenades and a Russian-made DShK heavy machine gun, known as a Dushka, trained on the nearest Islamic State position just visible on the horizon. And he said no new supplies had arrived.

He and most other members of Thuwar al-Raqqa are from Islamic State-controlled territory in Raqqa and asked to be identified only by their nicknames to avoid retribution against family members still living there.

U.S. officials insist that the ammunition was received by Arab fighters and that it is imminently to be used to bring “additional and renewed pressure on ISIL in the vicinity of Raqqa,” Army Col. Steve Warren told reporters at the Pentagon on Wednesday, using an acronym for the Islamic State.

A Pentagon spokesman, Col. Patrick Ryder, reiterated in an e-mail that the U.S. military has “high confidence that the ammunition we dropped was retrieved by the intended recipients, which were Syrian Arab groups fighting ISIL.”

According to YPG commanders, however, the supplies were always to be used at the discretion of a newly created umbrella entity, the Syrian Democratic ­Forces, which announced its existence on the day the ammunition was delivered. It includes Arab and Syrian minority groups but is overwhelmingly dominated by the Kurdish YPG, whose fighters outnumber the others in the alliance by a ratio of at least 4 to 1.

Haki Kobane, who commands a coalition of Arab and Kurdish forces­ fighting on the Raqqa front called Burkan al-Furat, or Euphrates Volcano, said the supplies could be deployed at any point along the 435-mile front line that the YPG maintains against the Islamic State, in many places without the participation of any other groups, Arab or otherwise.

Haki Kobane, a Kurdish leader in the Burkan al-Furat armed group coalition, speaks during a meeting with Arab Capt. Shamseddine, right. (Alice Martins/For The Washington Post)

“The Syrian Democratic Forces­ will decide which front the weapons will be given to, where the battle will be fought and who will get the weapons,” he said in an interview at the Euphrates Volcano’s headquarters in the town of Ain al-Aroush, near the Turkish border. In addition, “50 tons of ammunition is not enough to do anything,” he said. “We are fighting along a 700-kilometer front line.”

The leader of Thuwar al-Raqqa, who goes by the name Abu Issa, said the weapons were dropped in the neighboring province of Hasakah and were retrieved by the YPG.

“I don’t know where they went,” he said. “There are also front lines in Hasakah, so maybe the ammunition will be used there.”

The dispute surrounding the destination of this first supply of U.S. arms under the new Pentagon strategy is just one of several latent tensions over the future shape of the battle in northeastern Syria, where the Kurdish YPG has proclaimed a self-governing Kurdish enclave called Rojava.

Among them is the question of whether Raqqa should be a target at all, in a fight seen by Kurds as predominantly aimed at consolidating their control over Kurdish areas of northeastern Syria that were historically discriminated against during four decades of Assad family rule and now have fallen under Kurdish rule.

Rebels with the Thuwar al-Raqqa brigade hold positions in the front line against the Islamic State. (Alice Martins/For The Washington Post)

The tensions underscore the risk that this latest U.S. approach will become mired in complicated regional and local rivalries of the kind that have bedeviled, in different ways, so many of the other efforts to muster forces­ capable of confronting the Islamic State in its strongholds in Iraq and Syria.

The shift toward a Raqqa-focused strategy comes after the highly publicized collapse of the Pentagon’s $500 million program to train and equip a new Syrian army that would be dedicated to fighting the Islamic State. Syrian rebels balked at requirements that they abandon the fight against President Bashar al-Assad, and all but a dozen or so of the 130 who did receive the training were kidnapped by al-Qaeda, defected or deserted.

The latest plan, according to U.S. officials, envisages channeling resources­ earmarked for that program into supporting existing groups engaged in the fight in northeastern Syria, where the Kurdish YPG, backed up by Thuwar al-Raqqa, has made some of the most significant gains of the entire war along the vast perimeter of the Islamic State’s self-styled caliphate.

After blunting, then eventually rolling back the Islamic State’s assault on the Kurdish-Syrian town of Kobane earlier this year, with the help of U.S. airstrikes, the YPG-led force swept into the mostly Arab town of Tal Abyad on the Turkish border, the transit point for most of the foreign fighters and supplies reaching the militants’ territory and perhaps their most significant loss of territory yet.

From there, the Kurds and the Raqqa rebels pushed south, capturing scores of Arab towns and villages­ in the northern countryside of Raqqa province before coming to a halt in July in Ain Issa, a small, agricultural town tucked into a bend on the strategically vital international highway that runs across Syria from Iraq to the Mediterranean — and roughly coincides with the southern perimeter of the Kurds’ self-declared region.

The fight has now stalled on the southern edge of the town, which stands almost entirely empty. Collapsed roofs and walls offer testimony to the battles that raged, including the U.S. airstrikes that supported the offensive. Ain Issa’s overwhelmingly Arab inhabitants fled long ago, either south to the city of Raqqa along with the retreating Islamic State fighters or north into Turkey 40 miles away.

The YPG was accused in an Amnesty International report this month of forcibly displacing Arab villagers from their homes elsewhere in their self-governing enclave, and though they deny the charge, Kurdish officials recognize that extending the fight farther into Arab territory is likely to be both difficult and unwelcome among local inhabitants.

In Ain Issa, the Kurds and Thuwar al-Raqqa man separate outposts along the front line. The flags of the Free Syrian Army and the YPG both fly over the town. But the YPG controls the biggest base, at the local silo. Its fighters wear crisply identical uniforms; those of the FSA are dressed in mismatched gear or civilian clothing.

Most of the FSA fighters are from Raqqa, however, and they say they are eager to advance on the Islamic State’s capital, but only if they are given sufficient support. Ammunition alone would not be enough; the group needs heavier-caliber weapons as well, said Abu Awad, the local commander.

“The morale of our guys is very high, but we need support. We need weapons,” he said.

“We also need boots,” added Abu Mohammed al-Ansari, a gray-bearded fighter, pointing to the plastic sandals on his feet.

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