A US Navy Seal was killed in a firefight Tuesday with Islamic State in Iraq and Syria (ISIS) fighters in northern Iraq. It marked the third fatality suffered by US troops in “Operation Inherent Resolve,” launched by the Obama administration in 2014. Since then, over 5,000 US troops have been deployed to Iraq, while hundreds more are operating inside Syria.

The American special operator died after ISIS fighters used suicide bombings to blast through checkpoints manned by Iraqi Kurdish peshmerga forces, with which the Pentagon has allied itself in the region. The fighting took place outside the town of Tel Asqof, which is about 17 miles north of Mosul, previously Iraq’s second-largest city, which is now occupied by ISIS.

An offensive to retake the city has been predicted as early as next month or in June, but Tuesday’s fighting pointed to the immense contradictions underlying the US-backed anti-ISIS campaign.

The Kurdish peshmerga forces are among the main forces backed by Washington, which, as Tuesday’s fatality demonstrated, has deployed special operations troops with their fighting units. A conquest of Mosul, which is 90 percent Sunni Arab, by the peshmerga would represent an expansion of Iraq’s autonomous Kurdistan Regional Government (KRG) at the expense of the Sunnis.

At the same time, Shia militia backed by Iran, referred to as the Popular Mobilization Forces, have made it clear they intend to take a prominent role in the siege of the city. This threatens to provoke a further intensification of the bitter sectarian conflicts between Iraq’s Sunni and Shia populations that are the bloody legacy of Washington’s divide-and-rule strategy during the occupation that followed the US war of aggression against Iraq in 2003.

In a warning of the chaos that may ensue from the struggle by rival ethnic-based forces for the city, fighting raged for five days last month between Kurdish and Shia militias near the northern town of Tuz Khurmatu, which the two forces had together wrested from ISIS in 2014.

The Iraqi army, which has repeatedly proven itself a less than reliable force since it ceded Mosul to ISIS in June 2014, is largely viewed as a Shia force by the city’s Sunni population.

Further complicating the situation, Turkey, without Baghdad’s permission, has deployed several hundred troops and at least 20 tanks at a base in Mount Bashiqa, about 10 miles north of Mosul. The Turkish forces are also training and backing a 6,500-man militia loyal to Atheel al-Nujaifi, the former Sunni governor of the surrounding Nineveh province until the Iraqi parliament removed him from office on charges of corruption and collusion with ISIS.

Thus, an offensive for Mosul could rapidly degenerate into a multi-sided conflict with the potential of drawing in not only US forces, but also Turkey and Iran.

Any such march on Mosul may be delayed, however, by the mounting crisis of the US-backed regime headed by Prime Minister Hayder al-Abadi in Baghdad. Thousands of Shia militiamen have been withdrawn from the fight against ISIS and redeployed in the Iraqi capital in the wake of angry demonstrations against government corruption that saw last weekend’s storming of the Green Zone, the fortified enclave that is the center of the Iraqi government.

In addition to Shia armed factions that support the government, thousands of fighters loyal to Muqtada al-Sadr, the Shia cleric and political leader whose followers staged the protests, have also been brought back into Baghdad, taking up positions in Sadr City and elsewhere in the capital. Continuing tensions could easily trigger armed clashes between the rival Shia factions.

Following the report of the latest US fatality in Iraq, Defense Secretary Ashton Carter told reporters in Germany, “It is a combat death, of course, and a very sad loss.” He added that it showed that “it’s a serious fight that we have to wage in Iraq.”

Later in the day, White House spokesman Josh Earnest deflected a question as to whether US forces were being sent closer to combat, stating, “the president’s been clear time and time again exactly what their mission is. That mission is to support Iraqi forces on the ground who are taking the fight to [ISIS] on the front lines.”

Obama has deployed a growing number of US troops in Iraq after repeatedly foreswearing any “US boots on the ground” and claiming that those who have been sent there are not engaged in combat.

Amid the mounting crisis in Iraq, the UN, Moscow and Washington engaged in talks ostensibly aimed at restoring a cessation of hostilities in the Syrian city of Aleppo, where over 270 people have been killed in clashes between government forces and Western-backed Islamist militias over the past week and a half.

US and Russian military delegations were reportedly meeting to map out safe areas in the city and organize the monitoring of truce violations.

The Islamist forces, led by the Al Nusra Front, Syria’s Al Qaeda affiliate, pounded areas of Aleppo loyal to the government of President Bashar al-Assad Tuesday, killing at least 20 people and wounding scores more. Among the targets hit was a maternity hospital, where three women died.

The cease-fire deal reached on February 27 was broken by an offensive by the so-called “rebels” aimed at cutting off government-held areas of Aleppo, prompting a counter-offensive by Syrian army troops.

US Secretary of State John Kerry accused the Assad government of deliberately targeting hospitals struck last week, which he described as “unconscionable.” There was no such US condemnation of Al Nusra’s attack on the maternity hospital.

Kerry warned that if the Assad government failed to abide by the cease-fire, “there will clearly be repercussions, and one of them may be the total destruction of the cease-fire and they go back to war.” He added, “I do not think that Russia wants that. I don’t think that Assad is going to benefit from that, but there may be other repercussions that are being discussed.”

This was a veiled reference to a “Plan B” prepared by US military and intelligence agencies, which would respond to a breakdown of the so-called peace process with an aggressive escalation of the arming and support of the Islamist armed factions by Washington and its allies, including Saudi Arabia and the other Sunni Gulf oil monarchies. This would reportedly include supplying “vetted rebels” with MANPADS, shoulder-fired anti-aircraft missiles.

Such weapons could be used to bring down Russian fighter jets, escalating the threat of a wider war. They could also be turned against civilian passenger planes.