US Secretary of State John Kerry pressed for Iraq's help over the conflict in Syria during a surprise trip to Baghdad on Sunday amid claims of waning American clout barely a year after US troops left.
The one-day visit, the first to Iraq by a US secretary of state since April 2009, 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 met with Prime Minister Nuri al-Maliki and was to hold talks with parliament speaker Osama al-Nujaifi, to press Iraqi officials for greater cooperation on isolating the regime of embattled Syrian President Bashar al-Assad.
"It's good to catch up, it's good to see you again," Kerry told Maliki.
Referring to his last visit in 2006, when he was a US senator and Iraq was mired in brutal bloodshed, Kerry added, "I noticed things are calmer than the last time I was here," to which Maliki replied, "Inshallah (God willing)."
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 be very direct with Prime Minister Maliki about the importance of stopping the Iranian overflights and the transit across the territory, or at minimum, inspecting each of the flights," a State Department official said, speaking on condition of anonymity.
"He himself, as secretary of state, is convinced that they include weapons and fighters. ... This is dangerous for Iraq," the official added, while claiming that Iran was sending flights to Syria almost daily.
Baghdad has announced the inspections of two such flights, both in October 2012, but the New York Times reported in December that Iran appears to have been tipped off by Iraqi officials as to when plane inspections would be conducted, thus helping Tehran avoid detection.
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.
Kerry will also push for Iraq's Shiite-led government to better engage with its Sunni Arab minority, which has been protesting since December over the alleged targeting of their community by the authorities.
In particular, he was to press Maliki to reconsider a decision to postpone upcoming provincial elections, scheduled for April 20, in two large Sunni-majority provinces.
He will also call on Nujaifi, a senior leader in the Sunni-backed Iraqiya movement that is part of Maliki's unity cabinet but has boycotted government meetings, to urge ministers to return to the table.
"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 this month 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 and US officials have consistently disputed arguments that Washington's influence is waning.
"The full withdrawal of the US military ... reduced our leverage," Ryan Crocker, a former US ambassador to Iraq, said in an address to the Carnegie Council in Washington on March 21.
"It is time to engage in a serious, sustained and high level manner and through that engagement exert a greater influence with all the parties."
The visit to Iraq is Kerry's latest on a trip that has taken him to Israel, the Palestinian Territories and Jordan, all alongside US President Barack Obama.