IRBIL, Iraq/MURSITPINAR, Turkey: Iraqi Kurdish troops drove ISIS fighters from a strategic border crossing with Syria Tuesday and won the support of members of a major Sunni tribe, in one of the biggest successes since U.S. forces began bombing the Islamists.

 

The victory, which could make it harder for militants to operate on both sides of the frontier, was also achieved with help from Kurds from the Syrian side of the frontier, a new sign of cooperation across the border.

 

Iraqi Kurdish peshmerga fighters took control of the Rabia border crossing in a battle that began before dawn, an Iraqi Kurdish political source said.

 

“It’s the most important strategic point for crossing,” the source said.

 

The participation of Sunni tribal fighters in the battle against ISIS could prove as important a development as the advance itself.

 

Members of the influential Shammar tribe, one of the largest in northwestern Iraq, joined the Kurds in the fighting, a tribal figure said.

 

“Rabia is completely liberated. All of the Shammar are with the peshmerga and there is full cooperation between us,” Abdullah Yawar, a leading member of the tribe, told Reuters.

 

He said the cooperation was the result of an agreement with the president of Iraq’s Kurdish region after three months of negotiation to join forces against the “common enemy.”

 

Gaining support from Sunni tribes, many of which either supported or acquiesced in ISIS’ June advance, would be a crucial objective for the Iraqi government and its regional and Western allies in the fight against the insurgents.

 

Winning over Sunni tribes was a central part of the strategy that helped the U.S. military defeat a precursor of ISIS during the “surge” campaign of 2006-07. Washington hopes the new Iraqi government can repeat it.

 

Rabia controls the main highway linking Syria to Mosul, the biggest city in northern Iraq, which ISIS captured in June at the start of a lightning advance through Iraq’s Sunni north that jolted the Middle East.

 

Twelve ISIS fighters’ bodies lay on the border at the crossing after the battle, said Hemin Hawrami, head of the foreign relations department of the Kurdistan Democratic Party, one of the main Iraqi Kurdish parties, on Twitter. Syrian Kurdish fighters said they had also joined the battle: “We are defending Rabia ... trying to coordinate action with the peshmerga against [ISIS],” said Saleh Muslim, head of the Syria-based Kurdish Democratic Union Party (PYD).

 

If Rabia can be held, its recapture is one of the biggest successes since U.S.-led forces started bombing ISIS targets in Iraq in August.

 

Britain said its Tornado warplanes had launched their first attacks against ISIS in Iraq since parliament approved combat operations last Friday, targeting a heavy weapons position that was endangering Kurdish forces and subsequently attacking an ISIS armed pick-up truck in the same area.

 

Peshmerga liberated two villages 40 km south of Kirkuk from ISIS Tuesday, an Iraqi security official said.

 

Peshmerga Secretary-General Jabbar Yawar estimated the Iraqi Kurds had now retaken around half the territory they lost when the militants surged north toward the regional capital Irbil in early August, an advance that helped to prompt the U.S. strikes.

 

The U.S. military said it had conducted 11 airstrikes in Syria and the same number in Iraq in the previous 24 hours, on ISIS tanks, artillery, checkpoints and buildings.

 

ISIS fighters have laid siege to Kobani, a Kurdish city on Syria’s border with Turkey. Sporadic gunfire could be heard from across the frontier, and a bomb could be seen exploding in olive groves on the western outskirts of town.

 

A steady stream of people, mostly men, were crossing the border post back into Syria, apparently to help defend the town.

 

Ocalan Iso, deputy commander of the Kurdish forces defending the town, told Reuters Kurdish troops had battled ISIS fighters armed with tanks through the night and into Tuesday.

 

Turkey is likely to gain parliamentary approval for cross-border military operations in Syria and Iraq this week as ISIS insurgents threaten its territory, but it will be hesitant to send in troops without an internationally enforced no-fly zone.

 

ISIS Tuesday freed more than 70 Kurdish school children its fighters kidnapped in northern Syria in May, the Observatory said.

 

The Observatory said ISIS is refusing to hand over a further 30 children because it said they had relatives in a key Kurdish party.

 

In Damascus, Syria’s President Bashar Assad said extremists cannot be defeated by countries that have “spread terrorism.”

 

Speaking during a meeting with a senior Iranian official in Damascus, the Syrian leader took aim at countries he said backed “terrorists,” a term his regime uses for all those seeking his ouster. “Fighting terrorism can never be done by those countries that helped create terrorist groups, giving them logistical and financial help and spreading terrorism around the world,” state news agency SANA quoted Assad as saying.