At what point do US troops in Iraq become an occupation force?
Iraqi towns and cities were falling one after the other to the brutal, black-bannered forces of the Islamic State (IS) group in June 2014. After controlling much of the western Anbar province, the militants moved north, capturing the country's second-biggest city, Mosul.
The Iraqis had turned to the UN Security Council a month earlier, soliciting military support to stop the rise of IS. By early July, IS leader Abu Bakr al-Baghdadi took the podium at Mosul's Great Mosque of al-Nuri and declared himself the caliph of all Muslims.
With Baghdad in danger of falling to the militants, the administration of then-president Barack Obama agreed to send troops to Iraq to assist in an advisory capacity against IS. The deployment was based on diplomatic letters inviting American soldiers into the country and offering them immunity from prosecution under Iraqi law.
These so-called diplomatic notes, which are not public, remain the legal basis for the presence of about 5,000 American soldiers in Iraq today. According to experts and former US officials, the letters contain a provision that gives US forces one year to withdraw after they are formally asked by Baghdad to leave.
2014 diplomatic notes
As Iraqi politicians call on American troops to leave the country, the 2014 notes appear to remain in place.
Iraqi caretaker Prime Minister Adel Abdul Mahdi has said that he has requested that US Secretary of State Mike Pompeo send a delegation to Iraq to start working on a plan to "safely withdraw troops from Iraq".
"We're not at a point where the US and Iraq are enemies," said Abbas Kadhim, director of the Iraq Initiative at the Atlantic Center think-tank in Washington. "We are talking about allies that have differences, and they want to work out these differences in the best way, so they keep their alliance."
Hence, the Iraqi government has not formally requested an American military pullout in a legally binding way, Kadhim added. "They asked for negotiators to talk about the terms of withdrawal, which is understood or implied that the Iraqis want the US troops out, but they want to do it amicably."
If we leave, that would mean that Iran would have a much bigger foothold
- Donald Trump
The US envoy for the Coalition against IS, James Jeffery, has said the 2014 notes continue to provide the legal justification for American soldiers in Iraq.
"In terms of the US presence in Iraq, that is an issue between the United States and the government of Iraq, Baghdad," Jeffery told reporters on Thursday.
"It is based upon a 2014 exchange of notes between us and the foreign ministry that provides the legal presence of the United States as part of the coalition to defeat Daesh [IS] inside Iraq. That is where we are on that issue."
The 2014 letters came at a time of crisis. Three years earlier, the same Obama White House had refused to keep US troops in Iraq with only the assurances of the executive branch in Baghdad.
Legal immunity for US soldiers, which the Obama administration insisted in 2011, must be enshrined by the Iraqi parliament. Then-Iraqi prime minister Nouri al-Maliki said he would back such a legislative measure, but it was not clear that it would muster enough support to pass.
The last American combat troops left Iraq in December 2011, only to return in 2014 under much more perilous circumstances.
They asked for negotiators to talk about the terms of withdrawal, which is understood or implied that the Iraqis want the US troops out, but they want to do it amicably
- Abbas Kadhim, Atlantic Council
The hurried nature of the 2014 letters, which do not rise to the level of a treaty, makes them as easy to revoke as they were to implement.
But with Abdul Mahdi, who resigned late in November, operating in an interim capacity and the year-long deadline in the diplomatic notes, there is a long way ahead before the American military presence in Iraq becomes an illegal occupation.
Iraqi parliament resolution
Early in January, the Iraqi parliament passed a resolution calling on the government to expel US troops from Iraq.
The parliament's call came two days after US drone strikes killed top Iranian general Qassem Soleimani in Baghdad. The attack also claimed the life of Abu Mahdi al-Muhandis, a top Iraqi commander in the Iran-linked paramilitary group, the Popular Mobilisation Units (PMU).
The acting Iraqi premier, who still enjoys all of his constitutional powers, has suggested that it will be up to the new government to fully enforce the lawmakers' resolution.
Moreover, the Iraqi centres of power remain fragmented, with Kurdish and Sunni political parties largely wary of the push to drive out American forces and the government facing an ongoing wave of anti-corruption protests.
A official push by Baghdad to expel US troops may be a protracted process given the state of politics in the country, said Douglas Silliman, a former US ambassador to Iraq who is now the president of the Arab Gulf States Institute.
"Iraq's own inability to implement its laws in a timely manner and a clear manner is probably going to push this conversation through 2020, likely into 2021 unless there is a significant development, such as the legitimate selection of a very anti-American prime minister with a parliamentary majority that can back him on this," Silliman said at an event in Washington on Thursday.
Still, Shia politicians, including PMU leaders and influential cleric Moqtada al-Sadr, have been vocal in criticising the US military presence in the country and openly calling it an occupation.
Any conversations that the Iraqis want to have with us about the United States in Iraq, we believe should and must cover the entire gamut of our relationship
- James Jeffery, US envoy
On Friday, thousands of Iraqis gathered in Baghdad to call for US withdrawal.
Kadhim, of the Atlantic Council, called for negotiating an American military withdrawal from Iraq in a way that would ease the tensions of the past few weeks and preserve the strategic partnership between Washington and Baghdad.
He faulted both countries for voicing their frustrations publicly instead of resolving the issues diplomatically behind closed doors.
On the same day that Abdul Mahdi urged Pompeo to start negotiating a US withdrawal, the State Department issued a statement stressing - in no ambiguous terms - that American soldiers will not be leaving the country.
"America is a force for good in the Middle East," State Department spokeswoman Morgan Ortagus said in a statement on 10 January.
"Our military presence in Iraq is to continue the fight against ISIS and as the Secretary has said, we are committed to protecting Americans, Iraqis, and our coalition partners."
Kadhim said the "knee-jerk reactions" that Baghdad and Washington have been displaying are not helpful.
"At the end of the day, the United States cannot impose its troops on Iraq. There's no justification for keeping troops in Iraq against the will of the Iraqi people, and it's not in the interest of the United States to do that," he told MEE.
President Donald Trump has threatened to impose "very big sanctions" on Iraq if the US is forced to withdraw. He said American soldiers will eventually leave the country, but on Washington's terms.
"If we leave, that would mean that Iran would have a much bigger foothold," the US president said earlier this month. "And the people of Iraq do not want to see Iran running their country - that I can tell you."
Jeffery, the US envoy, also issued an implicit warning to Baghdad on Thursday.
At a news conference, he said that if the US and Iraq were to negotiate a troop withdrawal, everything else would be on the table, including Washington's diplomatic support to Baghdad.
"We're not interested in sitting down and talking only about withdrawal," Jeffry said.
"Any conversations that the Iraqis want to have with us about the United States in Iraq, we believe should and must cover the entire gamut of our relationship, which goes way beyond our forces, goes way beyond security."
Kadhim said imposing sanctions on Iraq would be harmful to both nations and counterproductive to Washington's stated aim of reducing Iranian influence in Baghdad.
"If this happens, the only winners from that would be Iran," Kadhim said. "The administration would need to ask this question: 'Do we want to give Iraq to Iran on a silver platter?'"
If the United States abandons Iraq politically, the only force to fill the vacuum would be Iran, he said.