Aid groups are warning that at least 50,000 civilians are in danger of being “caught in the crossfire” in Fallujah as it is subjected to constant US-led air strikes along with artillery barrages, and forces loyal to the Washington-backed government of Prime Minister Haider al-Abadi along with Shia militias encircle the central Iraqi city.

The predominantly Sunni city, which is about 40 miles west of the Iraqi capital of Baghdad, has been occupied by the Islamic State of Iraq and Syria (ISIS) since January 2014. It has now been targeted by the Iraqi government as part of a desperate bid to contain mounting political opposition from within Baghdad’s impoverished Shia population as well as from militia groups, including those aligned with the Shia cleric Moqtada al Sadr.

Within the last month, crowds numbering in the thousands have twice stormed Baghdad’s Green Zone, the heavily fortified seat of the Iraqi government. On the second occasion, on May 20, security forces repulsed the protesters with live fire, killing four and wounding hundreds.

Along with denunciations of the government for rampant corruption and a failure to provide essential services, the protesters have condemned it for failing to secure the capital from terrorist attacks, which have killed at least 200 this month, most of them in poor Shia neighborhoods.

Iraqi officials have claimed that the terrorist attacks have their origin in ISIS-controlled Fallujah, and the offensive is designed to show that it is doing something to halt these atrocities.

While the US military is providing air support for Iraqi government troops advancing on Fallujah—and denying it to the Shia militia forces of the Hashd al-Shaabi (Popular Mobilization Units), which work closely with Iran—Pentagon officials have made it clear that the siege of Fallujah is seen by Washington as a diversion from the principal strategic target in Iraq, the much larger city of Mosul in the north.

“You do not need Fallujah in order to get Mosul,” US Army Col. Steve Warren, the spokesman for the US military forces in Iraq and Syria, told the Reuters news agency in a telephone interview.

Nonetheless, Washington is supporting in Fallujah precisely the type of murderous siege that it has accused the government of President Bashar al-Assad of waging against areas controlled by the Western-backed Islamist “rebels” in Syria.

At least 21 civilians were reported killed in the US-led bombardment of Fallujah on Monday and Tuesday.

The population of Fallujah, which was the scene of bloody US sieges in 2004, has been subjected to bombardment for the last two years. Government forces have cut off supply routes to the city, depriving it of food, health care and other basic necessities. There are reports that substantial numbers of civilians are on the brink of starvation.

The Association of Muslim Scholars of Iraq, a militant Sunni organization formed in 2003, denounced the new offensive against Fallujah as “an unjust aggression, a reflection of the vengeful spirit that the forces of evil harbor against the city.” It reported in a statement that 10,000 Fallujans have been killed or wounded by government bombs and shells over the past two years.

While staying in Fallujah may entail starving to death, those who flee risk being killed by either ISIS or Iraqi government forces. As few as 80 families have managed to flee Fallujah.

The United Nations refugee agency has expressed concern over Iraqi government forces separating men and older boys from women and children, taking them to the Habbaniyah Military Base for “security screening.”

While the siege of Fallujah tightens in Iraq, a simultaneous offensive has been reported in the area north of the ISIS-held Syrian city of Raqqa.

Backed by US air strikes and accompanied by US special operations “advisors,” a force of several thousand fighters have begun advancing 30 miles to the north of the city. The Pentagon has described these fighters as belonging to the Syrian Democratic Forces, which is overwhelmingly dominated by the Kurdish People’s Protection Forces, or YPG.

The offensive was prepared by a secret visit to the Kurdish-controlled region of Syria by General Joseph Votel, the head of US Central Command, which oversees the US wars in the Middle East and Central Asia. Votel met with both Kurdish commanders and some of the hundreds of US special operations troops now on the ground in Syria.

The visit prompted an angry response by the Turkish government, Washington’s NATO ally, when Votel visited Ankara immediately after his unannounced foray into Syria.

Gen. Yasar Guler, the deputy chief of the Turkish General Staff, reportedly warned Votel against reliance upon the YPG, which Ankara fears will consolidate an independent Kurdish entity on its border. Instead, he proposed that Washington intensify its support for “moderate” Islamist rebels, forces which are largely dominated by either ISIS or the Al Nusra Front, Al Qaeda’s Syrian affiliate.

The group Raqqa is Being Slaughtered Silently, which regularly denounces ISIS atrocities against the city’s population, reported that US warplanes had dropped leaflets over the northern suburbs of the town, warning their inhabitants to flee the area.

The group pointed out, however, that there were no safe areas or access routes for such an exodus, adding via Twitter that the US reliance on the Kurdish dominated Syrian Democratic Forces to wage the offensive had pushed “a lot of people to join ISIS to defense of their city.”

Just as in Mosul and other predominantly Sunni areas of Iraq where the Iraqi army is seen as a hostile occupying force dominated by Shia interests, so in Raqqa, the SDF is seen as a hostile force dominated by Kurdish interests. In both areas, the local population fears, with reason, that they will be subjected to ethnic cleansing and driven from their homes.

In Iraq, there is already the example of Ramadi, the capital of Anbar province, whose “liberation” entailed the destruction of at least 70 percent of the city’s buildings. Since ISIS was driven out in December of last year, less than 15 percent of Ramadi’s previous population has been able to return.

The unfolding US-backed offensives in Iraq and Syria expose the catastrophe into which decades of US imperialist wars have plunged the entire region. The divide and conquer strategy employed by the US occupation in Iraq deliberately stoked sectarian tensions that have riven the country. Similarly in Syria, Washington and its regional allies have backed sectarian Sunni Islamist militias in a war that has claimed at least a quarter of a million lives.

Whatever the tactical victories achieved against ISIS, they will only exacerbate these divisions. US imperialism will continue its attempt to exploit them to further a military intervention whose underlying aim is not a struggle against terrorism, but rather the assertion of US hegemony over the Middle East and its immense oil wealth.