As the U.S.-led coalition ratchets up operations in Syria, there are concerns that it will result in a rerun of what happened in Iraq, where $1 billion in weapons supplied to local fighters is unaccounted for.
Weapons, training and airstrikes by the coalition have aided ground forces in both Iraq and Syria, allowing Iraq's military, Iraqi Kurdish fighters and Syrian Kurdish fighters to retake some 55,000 square kilometers (21,235 square miles) of territory from the Islamic State extremists in the nearly three-year fight.
However, many in both countries are concerned about how the forces bolstered by the coalition will leverage their influence and arms once the militants are vanquished. Numerous Iraqi groups that benefited from the training and arms have been accused of human rights violations.
The Trump administration's decision to provide Syria's Kurds with more advanced weapons has raised concerns among the various players in Syria's complicated battlefield. U.S. officials have said new weapons to be supplied would include heavy machine guns, ammunition, mortars and possibly TOW anti-tank missiles.
Coalition spokesman Col. John Dorrian said the weapons will not be reclaimed after the specific missions are completed but the U.S. will "carefully monitor" where and how they are used.
"Every single one" of the weapons will be accounted for and the U.S. will "assure they are pointed at" IS, he said.
But opposition fighters battling Syrian forces in the country's six-year civil war -- some of them backed by Turkey -- say there is simply no guarantee the weapons won't be directed against them or others.
U.S.-backed Kurdish groups have often clashed with Turkey-backed groups in northern Syria, where many factions are jostling to hold various zones of influence.
The coalition already has demonstrated an inability to track weapons in Iraq, a much less complex and unstable battlefield than Syria.
Amnesty International released a report this month detailing a 2016 U.S. Defense Department audit stating that $1 billion in weapons provided to Iraqi forces for use in the IS fight are now unaccounted for.
The coalition could have worked closer with the Iraqi government to ensure the weapons were accounted for, said Patrick Wilcken, a researcher with Amnesty and an author of the report. But in Syria, he said, it will be "almost impossible to avoid leakage and diversion of arms" provided by the coalition to fighters there.
"The coalition takes all reasonable efforts to maintain accountability of equipment divested to the government of Iraq to fight" IS, coalition spokesman Col. Ryan Dillon told The Associated Press. Since the 2016 audit referenced in the Amnesty report, he said, "all deficiencies identified in that report have been corrected."
Iraqi commanders must sign for all equipment they receive and the coalition then continues to monitor them "for future vetting purposes" and on the battlefield, Dillon added.
Allegations of torture, rape
This month, Germany's Der Spiegel magazine detailed allegations of torture, rape and killings of IS suspects at the hands of Iraq's Emergency Response Division, an Interior Ministry unit that has played a leading role in the coalition-aided operation to retake Mosul.
Iraqi soldiers, Kurdish forces and local policemen have all been accused of carrying out mass extrajudicial detentions of men and boys fleeing military operations against IS, according to reports by Human Rights Watch and the AP. Syrian Kurdish forces backed by the coalition have also been accused of abuses against Sunni Arabs, according to human rights organizations and Syrian opposition activists.
Other armed groups -- notably Iraq's mostly Shiite paramilitary forces who do not receive direct U.S. assistance of any kind -- have been accused of much more widespread human rights abuses than the forces backed by the coalition.
The U.S. human rights law known as the Leahy amendment prohibits the Defense Department from providing military assistance to foreign military units that violate human rights. In March 2015, the Iraqi Emergency Response Division was disqualified from receiving U.S. equipment and training, coalition spokesman Dillon said.
But he said the law does not prevent the U.S. from working with the ERD to help ensure a coordinated effort among different elements of the Iraqi security forces. The coalition has shared intelligence with the unit and conducted airstrikes to facilitate their military operations.
Iraq's Kurdish forces known as the peshmerga -- who have received some of the most extensive support from the coalition, including training, arms and air support -- have been accused of destroying Arab property and forcing Arab residents out of dozens of villages retaken from IS.
The AP visited one village outside Kirkuk where Arab residents said Kurdish forces labeled their homes as "confiscated," seized identification documents and reduced buildings to rubble. Iraq's Kurdistan regional government denied the claims, saying IS fighters destroyed the houses as they retreated.
Syrian Kurdish forces
In northern Syria, rebels are concerned that Syrian Kurdish forces will mirror the actions of the peshmerga and use the fight against IS to expand the land they control, ultimately creating a separate state by pushing out ethnic Arabs. Amid the chaos of the Syrian civil war, the Kurds have already created an autonomous Kurdish zone in northern Syria.
An Amnesty International fact-finding mission to northern Syria in 2015 uncovered forced displacement of Arab residents carried out by Kurdish forces that the group said amounted to war crimes. The report detailed the deliberate demolishing of civilian homes as well as razing and burning whole villages previously captured by IS. The Kurds have rejected the claims.
Col. Abdul-Razzak Ahmad Freiji, a Syrian army defector who is now with Turkey-backed rebels in northern Syria, said news of U.S. arms to Syrian Kurdish fighters exacerbates his concerns.
After the fight with the Islamic State group is over, Freiji said, "these weapons [will be directed] against us."