Given their tragic modern history, Palestinians are used to being trapped between Scylla and Charybdis in one form or another. But rarely has the situation been as stark and alarming as has now befallen the 18,000 remaining Palestinians and Syrians in the Yarmouk refugee camp just outside of Damascus.

Much of Yarmouk has been overrun by the fanatical terrorists of the Islamic State of Iraq and al-Sham (ISIS). The group’s familiar campaign of repression, beheadings and vicious abuse have already been reported in parts of Yarmouk. Meanwhile, Syrian government forces loyal to the dictatorship of Bashar al-Assad have been attacking the camp with the regime’s equally familiar deadly assortment of indiscriminate firepower, including the dreaded barrel bombs.

One resident reported that in Yarmouk, “people are trapped because of the clashes and the continuous and indiscriminate bombing. It’s hard to go out at all. But they can expect where the guerilla war will take place, but they can never predict where the barrel bombs will come. There is no water. People are running out of food.”

Christopher Gunness, of the United Nations Relief and Works Agency for Palestine Refugees (UNRWA), summed up the dire situation as “beyond inhumane.” He explained that “the camp has descended into levels of inhumanity which are unknown even in Yarmouk, and this was a society in which women died in childbirth for lack of medicine, and children died of malnutrition. Now ISIS have moved into the camp and people are cowering in their battered homes, too terrified to go outside. We in UNRWA have not had access since the fighting started, so there is no U.N. food, no U.N. water, no U.N. medicine. Electricity is in very, very short supply. It is astonishing that the civilized world can stand by while 18,000 civilians, including 3,500 children, can face potential imminent slaughter and do nothing.”

One child who fled the camp reported seeing “two members of ISIS playing with a severed head as if it was a football” on Yarmouk’s Palestine Street. Residents have reportedly been reduced to surviving on 400 calories a day. Those who have made it out are the lucky ones. Many are trapped and have nowhere to go.

It’s true that the humanitarian crisis in Syria is perhaps the worst since the Second World War, and that there are many millions of other refugees and displaced persons produced by this war. But the fate of the stateless Palestinian refugees has long and properly been considered to be a special international responsibility and concern, given the direct and proactive role of the League of Nations and the United Nations in producing the circumstances that led to their exile and dispossession. This is why it is particularly poignant when Palestinian refugees find themselves caught in tragic circumstances such as the Lebanese Civil War and now the catastrophic conflict in Syria.

Yarmouk is, therefore, a particular international responsibility. The UN Security Council held an emergency meeting on the crisis on Monday, but there is no indication that the international community intends to actually do anything about this calamity. Indeed, given the shameful “hands-off” approach to Syria that the West, and particularly the United States, has adopted, and the shameless support for the brutal Syrian regime by Russia and China, it’s not immediately clear what they could do about the tragedy in Yarmouk. This is what happens when options are intentionally foreclosed and responsibilities abandoned.

Beyond the humanitarian disaster that it entails, this development is politically catastrophic as well. It signals the arrival of ISIS in southern Syria and the direct environs of Damascus in a dramatic new level of engagement and strength. They are using the same methodology they did to rise in parts of the north and east of Syria two years ago. And there is no reason to think that, with determination and perseverance, they won’t be as effective in parts of the south as they have been in the other areas that have fallen under their control.

The attack on Yarmouk is part of a broader and alarming campaign by ISIS to establish a strong presence in the south of Syria. It is attempting, with considerable success thus far, to expand its footprint in Syria even as it is slowly rolled back in Iraq. It may have just lost control of Tikrit, but it has gained control of Yarmouk.

The Islamic State’s presence in the south gives it access to the slowly developing battle for Damascus and the ongoing fight over the strategically vital mountain region of Qalamoun, near the Lebanese border. There, Hezbollah has been one of the mainstays of regime power, and if ISIS supplants more moderate rebel groups in the south, we might see a protracted battle between the two groups over Qalamoun and other areas near the Lebanese border—possibly spilling over into northern Lebanon as well.

Meanwhile, the Assad regime is trying to use the crisis to draw Palestinians into its orbit, offering them arms and “firepower” if they agree to take them in an effort to expel Islamic State fighters. That would obviously be a disastrous mistake, and one which Palestinians are unlikely, in the main, to make.

But that means that the Palestinian refugees in Syria will continue to find themselves trapped between the ruthless and brutal forces of a dictatorship that coldly and often remotely kills people indiscriminately with devices of mass murder like barrel bombs, and a monstrous terrorist organization that enjoys killing people up close and personally through a variety of antediluvian techniques of horror, from decapitation to burning people alive and flinging them from the tops of high buildings.

The situation in Yarmouk was tragic enough already, particularly given the siege imposed on the camp by the regime, but it has just gotten infinitely worse. Unfortunately, there is still the potential for an even further deterioration. “The worst is not so long as we can say ‘This is the worst.'”

The international community may be shirking its responsibility, but that doesn’t mean the responsibility goes away. On the contrary, an urgent moral responsibility that is ignored only becomes a greater ethical conundrum, and a deeper indictment.