Security and economic challenges will be on the agenda as Iraqi Prime Minister Haider al-Abadi sits down with US President Donald Trump and other top officials in Washington this week.

Analysts say that the visit, Abadi's first since Trump took office in January, could usher in a new era of relations between Iraq and the United States - a situation that has left some Iraqis nervous. The meeting comes as the new US administration works to redefine its goals and interests in Iraq and throughout the region.

"I don't think Abadi can predict the new US policy outlines for Iraq," Hisham al-Hashimi, a researcher and counterterrorism expert at the Akkad Center for Future Studies in Baghdad, told Al Jazeera.

"There are fears that the new administration wants to limit the power of [the Iranian-backed Shia militias fighting ISIL] and also to cut the hands of Iran in Iraq and the region. Will [Abadi] be part of curtailing Iran's influence? He will be held in the middle between two parties."

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Trump has accused Iran of sponsoring "terrorism" in the region and being a destabilising factor in Iraq. During his presidential campaign, Trump criticised the 2003 war in Iraq and lambasted the Obama administration for allowing Iran to control Iraq.

After the pair met on Monday, Abadi's office issued a statement noting that Trump had stressed his "continuous support" to the Iraqi people in their ongoing fight against the Islamic State of Iraq and the Levant group ( ISIL, also known as ISIS).

"The two leaders agreed to continue their partnership in the long run to erase the roots of terrorism in Iraq and to support Iraq's military power and other crucial fields," the statement said, adding that the two countries would also enhance their political and economic partnership.

In addition to his sit-down with Trump, Abadi is due to attend a meeting of foreign ministers and senior leaders of the global coalition to defeat ISIL. The meeting, to be hosted by US Secretary of State Rex Tillerson on Wednesday, will deal with strategies to increase the pressure against ISIL in Iraq and Syria and to bolster humanitarian aid in areas recently retaken from the armed group.

Iraq's future relations with the US will depend on how the Americans decide to counter the Iranians. Are they going counter them politically or economically or militarily? Yahya al-Kubaisi, Iraqi Center for Strategic Studies

Trump, who has controversially suggested that the US should have "kept the oil" in Iraq after ousting former President Saddam Hussein, has also trumpeted plans to eradicate ISIL from "the face of the earth" - a pledge that could lead to a larger US troop deployment in Iraq. There are currently fewer than 6,000 American troops in Iraq and Syria.

"I think [Trump] will tell the Iraqis he wants to send more ground troops to Syria, Kuwait and Iraq to defeat ISIS. The key question that the Iraqis want to ask is how long these troops will remain on Iraqi soil," Lawrence Korb, a military analyst and a senior fellow at the Center for American Progress, told Al Jazeera.

Today, Iraq relies heavily on US political, diplomatic and military backing, but the future of this backing under a Trump administration remains unclear, Korb noted.

The 1991 Gulf war marked the beginning of US military involvement in Iraq, but after the 2003 invasion and the toppling of Saddam's regime, relations between Baghdad and Washington changed dramatically. More than 150,000 troops and US officials oversaw the drafting of a new political landscape in Iraq, ostensibly aiming to establish a democracy defended by its own army - but instead, Iraq was torn by sectarian strife, creating a fertile breeding ground for ISIL.

When US forces withdrew from Iraq in 2011, they left behind a weak government and a shaky power-sharing deal among Shia, Sunni and Kurdish parties, along with an army of diplomats and hundreds of military contractors at the biggest US embassy in the world. Under the Shia-led government of former Prime Minister Nouri al-Maliki, many Sunni residents of Iraq felt targeted and marginalised, leading to waves of protest.

Relations between Iraq and the US suffered another blow in January, when Trump issued a 90-day suspension of visas for nationals of seven Muslim-majority countries, including Iraq. The so-called Muslim ban, which was quickly overturned by a federal judge, was later replaced with a revised ban that excluded Iraq.

Iran, meanwhile, has emerged as the biggest winner in Iraq, consolidating its influence by forming and funding the country's powerful Shia militias, analysts say.

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Today, as the battle for western Mosul rages on, Abadi has said that ISIL is in its death throes, cornered in Mosul and isolated in Raqqa, the group's self-proclaimed Syrian capital. The global anti-ISIL coalition's main goal, beyond defeating the group militarily, is to destroy its safe havens and funding networks.

While the focus of the Trump administration in Iraq remains vague, senior US officials have suggested that countering the influence of ISIL and Iran are both top priorities, with Defense Secretary James Mattis calling Iran the world's "biggest state sponsor of terrorism".

"Although Abadi has said in the past that he intends to curb the influence of Iran and its militias, that's easier said than done," Korb said.

Yahya al-Kubaisi, a consultant and researcher at the Iraqi Center for Strategic Studies, told Al Jazeera that even after ISIL is pushed out of its Mosul stronghold, the role of the US in Iraq will not end, as ISIL will continue to maintain a lethal, if smaller, presence in the country.

"Iraq's future relations with the US will depend on how the Americans decide to counter the Iranians. Are they going counter them politically or economically or militarily?" Kubaisi asked. "The US backs Iraq militarily only to defeat ISIL. If the Abadi government doesn't listen, the Americans have options like supporting the Kurds and promoting Sunni federal regions."