"If the US said our objective is a strong and stable Iraq, then in many ways their best course of action would be to collaborate closely with the Iranians. But it's not. Their wish to counter the Iranian government in many ways overrides their wish to support the Iraqi state. There are contradictions in US policy in the region," he said.
Watling questioned what Trump's "maximum pressure" campaign against Iran was aiming to achieve. Iran's long-term strategy in Iraq, on the other hand, is paying off.
"We have seen a broadly unified attempt to ensure that Iran underwrites and limits Baghdad's military capability and that they retain Iraq as a market for their exports and as an economic partner," he said.
Winning hearts and minds
Despite achieving the regime change the US was looking for, with the capture and execution of Saddam, the US left Iraq in 2011 with an unsteady government in place. It had no choice but to send troops back to put out fires with the spread of ISIS. Iran also took part in the fight against ISIS, but it continued with its drive to boost influence in Iraq.
But Iran is failing in one key area. It hasn't really won the hearts of the people.
Anti-government protesters galvanized by deep economic grievances that have accumulated over many years have found themselves facing off with Iranian-backed forces.
Demonstrators were rallying against endemic corruption and cronyism, which they blame on "confessionalism," a system of government introduced by the US that divides power based on sectarian affiliation. While Iran didn't create that status quo, it has had a stake in maintaining it
In video footage of some of the demonstrations, protesters can be heard yelling chants against both Iran and the US. Young Iraqis in particular don't want either the US or Iran in their country, said Joost Hitermann, who leads the International Crisis Group's Middle East and North Africa program.
"Iraqis want to get rid of both. Some might like one more than they other, and they don't want just one of the two alone there, to dominate their country," Hitermann said.
"Shia Iraqis may be loosely aligned with Iran, but they don't subscribe to the Iranian Ayatollah Ali Khamenei. The Iranian way is not all what Shia Iraqis want."