BEIRUT — In a Middle East torn apart by war and conflict, fighters are increasingly using food as a weapon.

Millions of people across countries like Syria, Yemen and Iraq are gripped by hunger, struggling to survive with little help from the outside world. Children suffer from severe malnutrition, their parents often having to beg or sell possessions to get basic commodities including water, medicine and fuel.

The biggest humanitarian catastrophe by far is Syria, where a ruinous five-year civil war has killed a quarter of a million people and displaced half the population. All sides in the conflict have used punishing blockades to force submission and surrender from the other side – a tactic that has proved effective particularly for government forces seeking to pacify opposition-held areas around the capital Damascus.

Since October, Russian airstrikes and the start of yet another winter have exacerbated a humanitarian crisis and led to deaths from starvation in some places.

SCENES THAT ‘HAUNT THE SOUL’

Humanitarian teams who recently entered a besieged Syrian town witnessed scenes that “haunt the soul,” said Secretary-General Ban Ki-moon. He accused both the government of President Bashar Assad and the rebels fighting to oust him of using starvation as a weapon, calling it a war crime. Although sieges are an accepted military practice that are often carried out by forces seeking to avoid intense urban conflict, the conduct of forces carrying them out and their behavior toward civilian populations are regulated by international humanitarian law. Past cases include the sieges of Gorazde and Sarajevo during the Bosnian war. The Hamas-ruled Gaza Strip, home to 1.8 million people, has also been under an Israeli and Egyptian blockade, restricting the flow of many goods into the war-torn Palestinian territory.

The U.N. and aid agencies have struggled with funding shortages and growing impediments to the delivery of humanitarian assistance despite Security Council resolutions insisting on the unconditional delivery of aid across front lines.

In Yemen, the Arab world’s most impoverished nation, nearly half of the country’s 22 provinces are ranked as one step away from famine conditions.

Here’s a look at major areas in the Middle East under siege or suffering starvation:

SYRIA

The United Nations estimates more than 400,000 people are besieged in 15 communities across Syria, roughly half of them in areas controlled by the Islamic State group. In 2014, the U.N. was able to deliver food to about five percent of people in besieged areas, while today estimates show the organization is reaching less than one percent.

In 2015, the World Food Program was forced to reduce the size of the food rations it provides to families inside Syria by up to 25 percent because of a funding shortfall. The agency says it has to raise $25 million every week to meet the basic food needs of people affected by the Syrian conflict.

YEMEN

The humanitarian situation has dramatically deteriorated, nearly 300 days after the Saudi-led coalition began its air campaign aimed at driving Yemen’s Shiite rebels from cities under their control. Coalition naval ships are blockading traffic in Yemen’s ports and rebels are besieging several areas, particularly the southern city of Taiz.

Some 14.4 million Yemenis, more than half of the population, are food insecure, an increase of 12 percent in the last eight months, the U.N.’s Food and Agriculture Organization said Thursday. In late December, the WFP said 7.8 million of Yemen’s 24 million people are in even more dire condition, “facing life-threatening rates of acute malnutrition,” up by more than 3 million in less than a year. It said 10 of the country’s 22 provinces are in “the grip of severe food insecurity” at the “emergency” level, one step short of famine on the agency’s 5-level scale of food security.

IRAQ

Massive population shifts in Iraq due to violence has made it more difficult for millions of people to access food, medicine and safe drinking water. More than 3 million Iraqis are displaced within the country by violence and instability.

• A total of 8.2 million Iraqis are in need of humanitarian assistance: food, water, shelter or medicine, she said.