Baghdad (AFP) - Sunni Iraqi leaders who spearheaded a bloody insurgency against the 2003 US-led invasion are now the most nervous about a possible withdrawal of American troops, considered a counterweight to Iran.
Tensions between Washington and Tehran have boiled over onto Iraqi soil this month, with the US killing top Iranian general Qasem Soleimani in Baghdad and Iran striking back at an Iraqi base hosting American soldiers.
Furious at the US hit, Iraq's parliament held a vote on January 5 to oust all foreign troops, including some 5,200 American soldiers deployed alongside local forces.
All Kurdish and most Sunni MPs boycotted the session, despite threats by Shiite factions that the minorities would be considered "traitors" for backing the US presence.
Before the vote, speaker of parliament Mohammed Halbusi, a Sunni from the western Anbar province, made an impassioned appeal to MPs to reconsider.
"The decision we take now, we may not be able to amend in an hour's time," said Halbusi, addressing the mainly Shiite lawmakers in attendance.
"The US doesn't concern me. Iran doesn't concern me. Nothing concerns me as much as Iraq does," he said.
Both Iran and Iraq are Shiite-majority countries.
Tehran has cultivated close ties with Baghdad's ruling elite for decades.
It now exercises particularly strong sway through Iraq's Hashed al-Shaabi, a network of armed groups absorbed into the state security forces that has significant parliamentary representation.
Iran's growing clout has come at the expense of the US, which led the invasion that toppled Saddam Hussein whose dictatorial Sunni-dominated regime oppressed Shiites.
That unleashed a deadly insurgency, with Sunni militias attacking US forces, before a broad Iraqi sectarian war erupted in 2006-2007 costing thousands of lives.
- 'A buffer' -
Iraq's Sunni leaders now find themselves on the other side of the equation: Uneasy about perceived Iranian overreach, they are cautiously lobbying for US troops to stay.
Ahmad Jarba, a Sunni lawmaker from the northern province of Nineveh, told colleagues he was concerned a US withdrawal would mean an even bigger role for Tehran.
"After the vote, will our neighbours become our friends instead of our rulers? Or will we hand over our nation's decision-making to neighbouring countries?" Jarba asked.
The MP called on the government to rein in factions he accused of "blackmailing Sunni provinces and trying to turn them into military arenas".
Iraq's Sunni areas have been left ravaged by the fight against the Islamic State group, ultra-conservative jihadists who seized around a third of Iraq in 2014.
To defeat IS, the government partnered with both the Shiite-majority Hashed and a newly-formed global coalition led by Washington, which trained and assisted local troops.
Thousands of US-led coalition forces are still deployed at a half-dozen Iraqi bases, all in Sunni or Kurdish areas.
But the Hashed has also sought to increase its presence in those towns, which has irked Sunni residents.
"Our presence acts as a buffer in these areas," a US commander deployed at one of those bases told AFP, requesting anonymity as he was not authorised to talk to the media.
"The smaller our presence, the more defence actors could seek their own interests. Shiite, Sunni, Yazidi, different tribes -- their units would lash out against perceived threats," the commander added.
- 'Clear fear' of what's to come -
That distrust comes at a sensitive time.
Iraq's Shiite-majority areas have been rocked by months of anti-government protests that have called out Iran.
But Sunni areas have held back, afraid their own rallies would be seen in a sectarian light and would be quashed.
They are also nervously watching the escalating tensions between Iran and the US, but most have kept mum.
Some Sunni tribal sheikhs peeled away from the post-invasion insurgency to fight Al-Qaeda alongside the US in the so-called Sunni "awakening" of 2006.
Several told AFP they had received threats from armed factions.
"They warned us against siding with 'the occupier' again," one said, requesting anonymity due to security concerns.
"For Iraq's Sunnis, Kurds and other minorities, America creates balance with Shiite politicians who control the government," Iraqi expert Hisham al-Hashemi said.
Those minorities, he added, feared their Shiite rivals were leaning towards Iran "at the expense of the interests of the other components, and even at the expense of the Arab Shiite opposition."
"They think only America can deter this," said Hashemi.
But if Iraq's government forces a withdrawal, Sunnis may seek to instate an autonomous minority region, modelled after the northern region of Kurdistan, analysts said.
"There's a clear fear among Sunnis of what may come, which has prompted them to reconsider a canton to protect their own areas," said Ayad al-Tufan, an independent analyst and former army officer.