U.N. Secretary General António Guterres, center, and Somali President Mohamed Abdullahi Mohamed arrive for a news conference in Somalia's capital, Mogadishu, on Tuesday. (Feisal Omar/Reuters)

The new leader of the United Nations visited Somalia on Tuesday to issue a global appeal for aid as the war-torn nation teeters on the brink of its second famine in a decade.

It was António Guterres’s first field visit as U.N. secretary general, a position the former Portugal prime minister assumes during a time of historic humanitarian ­crises. South Sudan recently declared a famine, and three other countries — Somalia, Yemen and Nigeria — are on the cusp of similar disasters.

“Conflict, drought, disease — the combination is a nightmare,” Guterres said Tuesday.

More than 6 million Somalis, about half of the country’s population, are grappling with severe food shortages, according to the United Nations. At least 110 people, mostly women and children, died of malnutrition or a related disease in a two-day period in just one region earlier this month, according to the country’s prime minister.

Somalia’s hunger crisis is the result of two major factors — droughts that have badly damaged the country’s agricultural production and a protracted conflict that has obstructed humanitarian access to affected areas. Further complicating matters is the recent spread of cholera, which left 38 people dead last week.

Somalia has been in a near-constant state of turmoil since civil war broke out in 1991. Nearly 1 million Somalis have fled the country, and another million are internally displaced.

In 2011, famine consumed much of the Horn of Africa, killing nearly 260,000 people in Somalia alone, according to the United Nations. The international community subsequently determined that more must be done to prevent a similar disaster in the future. Yet as one of the U.N. officials briefing Guterres on Tuesday made clear, a lack of funding last year to help Somalis affected by drought contributed to the current crisis.

“With more resources last year, we would have been infinitely better off today,” said Peter de Clercq, the deputy special representative of the secretary general for Somalia. In 2016, the United Nations fell $240 million short of its $885 million funding goal for Somalia.

Now, Guterres is lobbying for a “massive response” to the worsening hunger crisis — $825 million in the first six months of 2017.

“Without that support, we will have a tragedy that is absolutely unacceptable,” he said.

So far, only $105 million has been received.

The situation in Somalia has not yet been declared a famine — a designation meaning that at least 30 percent of a population
is acutely malnourished and 2 adults or 4 children per every 10,000 people are dying each day. But de Clercq told Guterres that the situation was “rapidly deteriorating.”

During a trip to the crumbling southwestern city of Baidoa, scarred by years of fighting, the U.N. leader saw proof of that need. Hundreds of people had moved to an informal displacement camp after leaving drought-affected parts of the country, ­including some areas where Islamist al-Shabab militants were blocking the delivery of humanitarian supplies.

Their tents were made of whatever they could find — torn mosquito nets, bedsheets and towels. Inside, families of eight to 10 huddled, waiting for assistance. But little has arrived.

Guterres, wearing a white button-down shirt and a black bulletproof vest, walked from tent to tent asking people why they had fled their homes, whether al-Shabab was based near their villages and whether they had been fed in the camp.

Ugudow Mohammed Noor, a 52-year-old woman with a long thin face, left her village near the southern city of Kismayo last month with her seven children. They traveled mostly on foot for 15 days in the stifling heat to reach Baidoa.

“But there is still no food distributed,” she told a reporter, adding that she had taken to begging for scraps. Two days earlier, she said, her brother had died of cholera, an easily treatable disease caused by consuming contaminated food or water.

Of the four current hunger crises in Africa and the Middle East, Somalia’s is the most closely linked to environmental factors. Noor explained that as the drought intensified, she watched her six cows die one by one. Food for her family became increasingly hard to find, or afford.

Al-Shabab militants have made the situation worse. Checkpoints run by the group stop food from reaching those in need. Other times, insurgents levy a heavy tax on those distributing the rations.

Similar tactics led to thousands of deaths during the 2011 famine. This time, U.N. officials are hopeful that al-Shabab might be more willing to allow private food suppliers or humanitarian workers to pass.

“Last time there was a clear decision by al-Shabab to be obstructive,” said Michael Keating, the top U.N. official based in Somalia. “This time, there isn’t.”

In other countries dealing with famines or near-famines, aid workers have also struggled to reach the hungry. In South Sudan, the government has created “administrative and bureaucratic impediments” for humanitarian groups, said Stephen O’Brien, head of the U.N. Office for the Coordination of Humanitarian Affairs.

In northeastern Nigeria, aid workers have been unable to reach desperate people because of military restrictions and the threat posed by Islamist Boko Haram fighters. In Yemen, clashes between pro-government forces and Houthi rebels have made it difficult for aid groups to travel.

Across the four countries, the United Nations estimates that 20 million people are caught up in hunger crises.

“In modern world history, we’ve never confronted the prospect of four major famines in four countries,” O’Brien said.

But with the Trump administration planning to propose large cuts to foreign aid, the United Nations cannot count on its largest donor to help fill the massive funding shortfall.

Guterres visited a day after President Trump introduced a revised travel ban that would temporarily bar Somalis and people from five other countries linked to terrorism from entering the United States. The new U.N. chief said that extremists will benefit if the international community neglects this country.

“To address in an effective way the risk of famine is to support the stabilization of Somalia,” he said. “It’s the best way to address the root causes of terrorism.”

Last month, Somalia elected a new president, Mohamed Abdullahi Mohamed, who quickly declared the drought a national emergency. “We know many animals will die,” Mohamed said at a news conference Tuesday, “and of course people will follow.”