By Isabel Coles
ARBIL, Iraq, Oct 31 (Reuters) - Cloaked in Kurdish flags, thousands of people lined the roads to cheer on a military convoy headed for what was -- until recently -- an obscure Syrian border town, now the focus of a global war against the militants of Islamic State.
The Iraqi Kurdish peshmerga were on their way to help fellow Kurds defend Kobani in a battle that has assumed huge significance in the United States' campaign to "degrade and destroy" the hardline Islamist insurgency.
It is unclear whether the small but heavily armed contingent of peshmerga will be enough to swing the battle, but the deployment is a potent display of unity between Kurdish groups that more often seek to undermine each other.
The unified front is being forged as Kurds emerge as the West's most trusted and effective partner on the ground in both Iraq and Syria.
But preserving that unity be tricky, given the competing ambitions for leadership of the world's more than 30 million Kurds, the majority of whom are Sunni Muslim, but who tend to identify more strongly with their ethnicity than religion.
Governments in each of the four countries across which they are spread - Iraq, Syria, Turkey and Iran - have tended to exploit internal Kurdish divisions to thwart their aspirations for independence.
"We all want the Kurdish people to be united," said 33-year old Ayyoub Sheikho, who fled Kobani last month and is now living in a newly pitched row of tents at a refugee camp in Iraq's Kurdistan region. "If we don't unite we will be trampled on."
Fuad Hussein, the Kurdistan president's chief of staff, said Islamic State had "destroyed the borders."
"It is the same terrorist organization that attacks in (the Iraqi towns of) Khanaqin in Jalawla in Mosul in Kirkuk but also in (Syrian) Kobani, so this created a feeling of solidarity among the Kurds," he told Reuters.
The deployment of peshmerga to Kobani illustrates the unprecedented degree of cooperation that has emerged between Kurdish groups across borders since Islamic State overran a third of Iraq this summer and proclaimed a caliphate straddling the frontier with Syria.
When Islamic State targeted Iraqi Kurdistan in August, fighters from the Kurdistan Workers' Party (PKK) descended from mountain bases on the Turkey-Iraq border to help blunt the offensive.
Around the same time, fighters from a Syrian Kurd group that has surged to promince during the civil war there -- the People's Protection Units (YPG) -- crossed into Iraq to save thousands of minority Yazidis from death at the hands of Islamic State militants who had torn through the peshmerga's defenses.
Kurds from Iran have also been fighting alongside peshmerga forces in Iraqi Kurdistan.
"Kurds today are more unified than ever before, and even if they were to take a few steps back, they will still be much further ahead than they were six months ago," said Henri Barkey, a former State Department official who now teaches at Lehigh University in the United States. "The upshot of all of this is a consolidation of Kurdish national identity."
If Kobani were to fall, officials in Iraqi Kurdistan say they fear a domino effect on Syria's two other Kurdish "cantons," precipitating a fresh wave of refugees into the autonomous region, already struggling to accommodate more than 1 million people displaced by violence within Iraq.
It would also boost the morale of Islamic State in Iraq, where the peshmerga have been regaining ground in the north since U.S. air strikes began in August.
Nevertheless, some question why Iraqi Kurds have deployed peshmerga abroad when they are still stretched at home, and have yet to win back all the territory they let slip.
The decision to reinforce Kobani was made under intense popular pressure from Kurds worldwide.
Barzani's efforts to extend his influence across the border into Syria have been repeatedly frustrated by the Democratic Union Party (PYD), the political wing group of the YPG militia, which has emerged as the dominant Kurdish force there.
Rival Syrian Kurdish parties backed by Barzani have looked increasingly irrelevant by comparison. The U.S. government held its first publicly acknowledged meeting with the PYD in October and the YPG says it has been coordinating air strikes with the U.S. military during the Kobani campaign.
Relations between the Kurds in Iraq and Syria have been rocky.
Hundreds of Syrian Kurds trained under Barzani's auspices in northern Iraq, but the PYD refused to let them back in, saying its own YPG militia was the only legitimate armed force.
In turn, PYD leaders were denied entry to Iraqi Kurdistan, and, earlier this year, the regional government dug a trench along its frontier with Syria, citing concerns about Islamic State infiltration.
The PYD said that was a clear attempt to throttle its nascent administration, which the Iraqi Kurds did not officially recognize until this month.
But, in another sudden sign of unity, the Syrian PYD -- which some say has been tarnished by its association the Turkish militant group PKK -- struck a power-sharing deal with other Syrian factions last week, a move aimed at least in part to improve its image abroad.
COMMANDER IN CHIEF
As the peshmerga convoy departed Iraqi Kurdistan for Turkey, en route to Kobani, Kurds held aloft framed portraits of Barzani and his father, Mullah Mustafa, revered as a pillar of Kurdish nationalism. Some prostrated themselves in the road.
By deploying the peshmerga -- of which he is commander in chief -- to Kobani now, Barzani is boosting his credentials as a transnational leader of the Kurds and their interlocutor with the West.
A senior member of a rival party in Iraqi Kurdistan said the move would also help boost Barzani's popularity after setbacks on the battlefield this summer, and mend some of the political damage inflicted by his perceived over-reliance on Turkey, which failed the Kurds in their time of need.
Turkey is one of Iraqi Kurdistan's closest political and economic allies, yet Ankara fears that if Syria's Kurds follow the example set by their brethren in Iraq and seek an independent state in northern Syria, it could embolden Kurdish militants in Turkey and derail a fragile peace process.
Turkey's reluctance to support the fight against Islamic State over the border in Syria enraged its own Kurdish minority, complicated efforts to provide aid to Kobani and meant negotiations to enable the passage of the peshmerga through Turkish territory were delicate and complex.
Rival groups' links to different regional powers, remain a threat to Kurdish unity, according to Maria Fantappie, Iraq analyst with International Crisis Group.
"I see this as a temporary convergence of interest more than lasting realignment," she said. "Beside ideological differences dividing KDP (Barzani's party) and PYD, these two parties' regional ties, with Turkey and Iran respectively, remain the largest impediment to the formation of a united Kurdish front." (Editing by Michael Georgy and Robin Pomeroy)