US Secretary of State John Kerry made a surprise trip to Baghdad on Sunday to push Iraq for more help over the conflict in Syria amid claims of waning American clout barely a year after US troops left.
The visit, his first to Iraq since taking office, will also focus on concerns in Washington that months of protests in the country's Sunni-majority provinces will give militant groups including Al-Qaeda room to manoeuvre.
It comes just days after the 10th anniversary of the US-led invasion of Iraq that ousted Saddam Hussein and sought to establish a stable democratic ally in the heart of the Middle East, but has instead left a country still grappling with deadly violence and endless political disputes.
Kerry will meet Prime Minister Nuri al-Maliki and parliament speaker Osama al-Nujaifi and press Iraqi officials for greater cooperation on isolating the regime of embattled Syrian President Bashar al-Assad.
Washington has accused Baghdad in particular of turning a blind eye as Iran sends military equipment through Iraqi airspace, flights which Tehran insists transport only humanitarian supplies.
Kerry "will talk about the importance of Iraq participating (in meetings about the future of Syria), but at the same time it would not be appropriate for Iraq to participate so long as it is facilitating Iranian overflight of fighters and weapons that support Assad," a US State Department official said.
"The key here is to discuss the political future of Syria -- Iraq should be part of that -- but it should be on (the) basis that Assad has to go, not on the basis of permitting continued Iranian support for Assad," the official added, speaking on condition of anonymity.
A US official this month called on Iraq to resume unannounced inspections of Iranian flights bound for Syria, after Baghdad stopped two planes in October.
"They are suspending their disbelief, looking the other way, and averting their gaze," the official said.
Iran has remained a steadfast ally of Assad's regime despite the conflict in his country which according to the United Nations has killed more than 70,000 people since it erupted in March 2011.
America's top diplomat will also push for Iraq's Shiite-led government to better engage with its Sunni Arab minority, which has been holding ongoing protests since December over the alleged targeting of their community by the authorities.
In particular, Kerry will push for Maliki to reconsider a decision to postpone provincial elections, scheduled for April 20, in two large Sunni-majority provinces, which the State Department official said was a "serious setback".
"Secretary Kerry will be talking with Prime Minister Maliki about the importance of engaging with all elements of Iraqi society, with the Sunnis, to work out how best to counter the very serious terrorist threat that is (of) deep concern to Iraqis," the official said.
A Western diplomat warned last week that Washington was concerned by "the vacuum that it (protests in Sunni provinces) creates for Al-Qaeda to come in and play a role."
Kerry's visit comes amid claims of declining American influence in Iraq, in particular following the December 2011 withdrawal of US forces, and concerns that Baghdad's Shiite neighbour Iran wields greater clout.
The American mission to Iraq, however, remains the biggest in the world with 10,500 staff at its embassy in Baghdad as well as its consulates and other smaller sites, and US officials have consistently disputed arguments that Washington's influence is waning.