Kurds watch the Syrian town of Kobane from the Turkish border. (Bulent Kilic/AFP/Getty Images)

Turkey said Monday that it would allow Iraqi Kurdish fighters to cross its border into the besieged Syrian town of Kobane, where Syrian Kurds are battling Islamic State militants.

The opening of a land corridor would be another potential boost for the Kobane defenders following U.S. airdrops of weapons, ammunition and medical supplies to them late Sunday.

But the deal, the subject of intensive U.S. diplomatic talks over the past week, also depends on whether the separate Kurdish groups can resolve their deep differences in the interest of confronting a common enemy.

The tentative nature of the agreement reflected the convoluted history and political calculations of all parties, particularly the Kurds, whose ethnic homeland spreads across Syria, Turkey, Iraq and Iran.

Turkey had opposed delivering weapons to Kobane’s Syrian Kurds because of their affiliations with the Kurdistan Workers’ Party (PKK), a group based in southeastern Turkey that has fought Turkish forces since the mid-1980s, seeking greater autonomy. Its leaders have threatened to tear up a recent peace accord with Turkey if Kobane falls.

Turkey and the United States have declared the PKK a terrorist organization, raising additional complications for American policy­makers.

While the United States understands Turkey’s concerns, Secretary of State John F. Kerry said Monday during a visit to Indonesia, “We cannot take our eyes off the prize here. It would be irresponsible of us, as well as morally very difficult, to turn your back on a community fighting ISIL, as hard as it is, at this particular moment.” ISIL is one of several acronyms for the Islamic State.

For its part, the main Syrian Kurdish party, the Kurdish Democratic Union (PYD), is wary that its power could be undermined by allowing the more politically connected Iraqi Kurds, who maintain close ties with the West and relatively good relations with Turkey, to join their fight.

Idriss Nasaan, a spokesman for the Kobane Kurds, said the Iraqi Kurdish fighters will be welcome only if they “agree to fight under the command” of the local leadership.

Kerry acknowledged that the fighters in Kobane “are an offshoot group of the folks that our friends, the Turks, oppose.” But, he said, “they are valiantly fighting ISIL.”

As recently as last week, the Obama administration said that control of Kobane was not a “strategic” objective for U.S.-led forces conducting airstrikes against the Islamic State and that operations there were humanitarian in nature. But with militant forces surging toward the town, U.S. commanders have also stepped up airstrikes.

American warplanes have now struck the area around Kobane more than 135 times, far more than any other location since strikes began in Syria at the beginning of this month. Those strikes continued Monday, including one that the U.S. Central Command said blasted a “stray” shipment from the American airdrop to prevent “these supplies from falling into enemy hands.”

The administration has said repeatedly that airstrikes are not enough and that defeating the Islamic State will depend on local ground forces in Syria and Iraq.

Turkey had tentatively agreed late last week to allow the Iraqi Kurdish fighters, called pesh merga, to travel to Kobane. The deal was nearly upset, however, when U.S. officials publicly acknowledged that they had held direct talks with representatives of the Syrian Kurds.

Turkish President Recep Tayyip Erdogan told reporters Saturday that he considered the Syrian PYD “the same as the PKK, and that is a terrorist organization.” Referring to reports that the United States was considering sending arms directly to the Syrian Kurdish fighters, Erdogan said that “it would be wrong” to expect full Turkish participation in the coalition against the Islamic State “if a friendly country and a NATO ally like the U.S. openly admits such support for a terrorist organization.”

But when the situation in Kobane worsened, the administration feared that the town would be lost to the militants before any deal could be implemented.

Under a barrage of Islamic State mortar fire over the weekend, the Kobane defenders warned that they were nearly out of ammunition, according to senior administration officials. The Pentagon told the White House it could drop emergency supplies into the town, amid administration concern that the Turks would back out.

Turkey’s agreement stood, however, after Obama called Erdogan late Saturday to tell him that the planned airdrop was an emergency measure only and did not constitute a change in U.S. policy. Officials said the arms themselves had come from the Iraqi Kurds and were not “U.S.-produced” weapons.

The primary weapon used by the pesh merga is the Russian-made AK-47 assault rifle, and the United States previously arranged for Albania and other former
Soviet-bloc countries that are now part of NATO to provide those fighters with additional supplies. The airdrops to the Syrian Kurds, who also use AK-47s, came from those Albanian shipments, said a senior U.S. official, speaking on the condition of anonymity to provide information beyond that included in official statements.

Early Monday, Turkish Foreign Minister Mevlut Cavusoglu said the pesh merga would be allowed to cross into Kobane. “We never wanted Kobane to fall,” Cavusoglu told reporters in the Turkish capital, Ankara.

Although Turkish media reported that the movement of the Iraqi forces into Kobane had already begun, U.S. officials said they expected the next 24 hours to be decisive in reaching a firm agreement among all parties, including the Syrian Kurds.

The president of Iraq’s Kurdish region, Massoud Barzani, ordered pesh merga units “to be deployed in Kobane in the next 48 hours via Turkey,” according to a Monday statement sent via Twitter by Hemin Hawrami, the foreign relations chief of Barzani’s ruling political party.

Turkey also has tried to leverage its support for the coalition effort to secure a U.S. pledge to expand its military campaign against the Islamic State into a fight against Syrian President Bashar al-Assad.

Cavusoglu said Turkey also wants Syrian Kurds to unite against Assad and give up demands for autonomy over their region in order to receive Turkish aid.

But those longer-term concerns have clearly been overridden in recent days by events in Kobane. “It is a crisis moment,” Kerry said, “an emergency where we clearly do not want to see Kobane become a horrible example of the unwillingness of people to be able to help those who are fighting ISIL.”

DeYoung reported from Washington. Brian Murphy in Washington contributed to this report.