With their escape route to the United States endangered by the orders of President Donald Trump, the people of Somalia now face a new threat: a looming famine that could bring starvation to millions.

Just six years after a famine that killed a quarter of a million Somalis, the United Nations is warning that the war-ravaged country could face another catastrophe this year, unless there is a “massive and urgent” increase is humanitarian aid.

Somali refugees are already suffering two other crises. A crackdown by Kenya and the United States has jeopardized their hopes of finding haven abroad. And a continuing insurgency by Islamist militants has made it dangerous to return home.

After two consecutive seasons of failed rains and widening drought in Somalia, hunger and malnutrition are spreading. Even as the country is still recovering from the last famine, more than half of its entire population needs humanitarian aid today, the UN says.

Since September, the number of Somalis needing humanitarian assistance has increased from five million to 6.2 million, the UN says.

Relief agencies say the warning signs in Somalia today are similar to those in the months before the 2011 disaster – the worst famine of the 21st century. The world paid little attention to the repeated warnings issued by relief agencies at that time, until the famine struck. Only then did large-scale aid begin to flow. This time, agencies are pleading for donors to take action before famine hits.

Children are again suffering the worst effects. About 363,000 acutely malnourished children are in desperate need of “critical nutrition support,” according to Peter de Clercq, the UN’s humanitarian coordinator for Somalia.

This includes more than 71,000 severely malnourished children who need life-saving treatment, he said.

“The situation we are starting to see in many rural areas today … is starting to look worryingly like the run-up to famine in 2010-2011,” said Richard Trenchard, the representative in Somalia of the UN’s Food and Agriculture Organization.

“Most striking is the pace, scale and geography of deterioration, and the potential for the situation to become much, much worse,” he said in a statement.

“Labour prices are collapsing, local food prices are rising, food availability is becoming patchy, animal deaths are increasing, and malnutrition rates are rising, especially among children. Together, these are all signs that we are entering a phase that can lead to catastrophe.”

Hunger, drought and war have already pushed two million Somalis to become refugees. Somalia is today the world’s third-biggest source of refugees, behind only Syria and Afghanistan.

Yet their safe havens are rapidly dwindling. Traditionally they took shelter at the huge Dadaab camp in northern Kenya, one of the world’s biggest refugee camps. From there, they could seek resettlement in the United States, Canada and other countries. But now Kenya is trying to shut the Dadaab camp, and the U.S. administration is seeking to impose severe limits on the flow of refugees from Somalia and six other Muslim-majority countries.

Last month, Mr. Trump ordered a 90-day halt in all travel to the United States by people from the seven countries. A judge has overturned the travel ban, but the Trump administration is fighting a legal battle to impose the ban again.

Nearly 15,000 Somali refugees at the Dadaab camp, who had planned to resettle in the United States, have been stranded at the refugee camp as a result of the Trump order. Others who were in transit in Nairobi, heading to the United States, have been sent back to the camp.

The threat of famine could force even more Somalis to flee their homes. One humanitarian agency, Save the Children, is warning that millions of Somali children are at risk of starvation and even death unless urgent aid is provided by June.

After the back-to-back failed rains, Somalia has been hit with severe water shortages, and many families are forced to buy water from trucks. Some regions of the country have endured the driest year in three decades. The price of a 200-litre barrel of water has tripled, while cereal production has dropped by 75 per cent and three-quarters of Somalia’s livestock has died, according to a report by Save the Children.

“With the spring rains expected to be much lower than average, we have a small window to stop what happened in 2011 from happening again – but that window is quickly shutting,” said a statement by Hassan Saadi Noor, the agency’s country director in Somalia.

To avert another famine, the UN is urging the international community to raise $300-million (U.S.) in emergency funds for Somalia by April.