He sits behind a table in an air-conditioned living room, within a house in a guarded United Nations compound wearing a casual t-shirt and the broadest grin he's had in seven years.

David Shearer is in his element as the head of the United Nation's mission in the world's youngest country - South Sudan - where he's leading one of its biggest and most difficult international peacekeeping missions, with 15,000 uniformed and almost 2000 civilian staff, and a budget of nearly $1.6 billion.

It is the dry season and the temperature reaches 45 degrees Celsius most days.



Dust clings to everything at the UN compound in Thongpiny, inside Juba - the South Sudanese capital.



He seems at home, even though he is living in a compound encased with barbed wire, has a team of bodyguards and security detail that follow him everywhere he goes, a 7pm curfew each night and eats chicken and rice for lunch five days a week.



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​His neighbours are the nearly 40,000 South Sudanese from the Nuer ethnic group who have fled civil unrest and persecution by the Dinka, many who make up the Government.

NERRIS MARKOGIANNIS/UNMISS David Shearer at work for the UN in Leer, South Sudan

The Nuer had literally nowhere else to run, but into the UN compound.

Shearer flew in on January 20 - the day Donald Trump was inaugurated as US president and just weeks before famine was officially declared in South Sudan.

It's enough to make anyone balk - a country that fought so long for independence, gained it in 2011, but fell apart soon after when it was ripped apart by civil unrest.

SIEGFRIED MODOLA/REUTERS Internally displaced South Sudanese gather by a water collection point next to a camp in a United Nations Mission in South Sudan.

But not Shearer – he's at ease in this conflict-driven emergency.



So far 2 million people in South Sudan have been uprooted by the violence: ethnic cleansing, murder, rape, corruption and looting and torching of houses.



Another 1.5 million have become refugees in neighbouring countries.



Shearer is a world away from his wife and two children and their comfortable Pt Chevalier home, in what was his Mt Albert electorate, let alone from New Zealand's corridors of power – Parliament.

It was here Shearer lost his inner calm, particularly while he led Labour from 2011 to 2013, a time when he seemed caught in the headlights, bumbling and a tad shell shocked.

He concedes his roots within the party weren't strong enough and the perception that we has more centrist than his colleagues alienated him.

SANDRA MU/GETTY Shearer spent seven years in the Labour party, but resigned in 2016 in order to take up his post as head of mission in South Sudan.

Ultimately he calculated his losses after seven years with Labour - he wasn't satisfied with the direction the party was taking and he wasn't being challenged.

During several trips to New York in 2016 he was asked for his CV by the head of UN's peacekeeping operations and several months later he was made a firm job offer.

"All of a sudden it was happening - I had been wanting to do something that made a difference."

REUTERS A South Sudanese refugee family arrives at the UNHCR refugees reception point at Elegu near the South Sudan-Uganda border.

He was heading back to New York on a flight on December 5 when John Key resigned as Prime Minister.

"I had already made up my mind to take this job, but I hadn't told anyone - but Key knew through the Government grapevine - I'd spoken to Murray McCully."

Shearer switched on his phone when he landed and his phone went crazy with messages and alerts of the news.

JAMES AKENA A South Sudanese refugee family share a meal at the UNHCR managed refugees reception point at Elegu, near the South Sudan-Uganda border.

"Most people said there had to be another agenda, but I said this guy has made a courageous decision - most politicians don't leave on their own terms - they leave on someone else's."

Shearer's mind was made up about his own exit, and it was announced days later.



He and Key have that in common, they made their move on their terms.

Shearer gave a rare glimpse into the toll of that political period in his farewell speech to Parliament.

SIEGFRIED MODOLA/REUTERS Women hold their babies as they wait for a medical check-up at a UNICEF supported mobile health clinic in Nimini village, Unity State, South Sudan.

"I haven't been in Government, I haven't been in Cabinet and I didn't get to be the Prime Minister".



"For me, the Labour leadership was both a highlight and, obviously ultimately a disappointment."

He welled up when he recalled his daughter asking him why people were mean to him.



He replied it was because he was a politician, she replied, "they should remember that you're a human being as well".



"It's tough for kids to see their parents attacked in the media and it's impossible to hide it from them."



Now, he doesn't have to jump through the same hoops as he did in Parliament.

He's articulate and qualified for the job – with over 20 years working in some of the world's most hostile places for the UN – including as head of the UN Office of the Coordination of Humanitarian Affairs in the Occupied Palestinian Territories.

SUPPLIED Nyanken Ruot holds her baby Both Tebg, a 2-month- old child with severe malnutrition, at the malnutrition ward of the clinic run by the International Medical Corps In Juba, South Sudan.

He has also worked in Somalia, Liberia, Rwanda, Lebanon, Afghanistan, Iraq and the Balkans.

Now that he's still in the hot-seat with a logistical nightmare on his hands he seems remarkably calm about it.



In a population of 11.5m, nearly a third of South Sudanese are displaced and just over a half of them will need food aid this year.



It's a race against time - Shearer and his staff have less than a month to get food and supplies in place for the South Sudanese, and for troops at the UN's 10 major bases and seven minor bases across the country.



Rainy season starts from about late April and can span right through until October causing widespread flooding and infrastructure to shut down.



During the rainy season you simply can't get to most places, so Shearer and his team have to act quickly.



It's a logistical nightmare - the 1000km road connecting Juba, where Shearer is based, and Bentiu, where the UN has it's largest protected camp for 120,000 internally displaced South Sudanese - is impossible to pass six months of the year.



It should take about 12 hours to drive, instead on a bad run it can take up to two weeks.



Only a short portion of the road is sealed, and the rest is rough, filled with sinkholes and dirt and plagued by 90 checkpoints along the way.

"It's a process of being stopped, and arguing along the way," says Shearer.

SUPPLIED Flora Fai (centre) holds her twins, (left to right) Kegi and Yada Jacob, both with malnourishment, at the malnutrition ward in Al Shabbab hospital in Juba, South Sudan.

Most of those checkpoints are controlled by South Sudanese soldiers who've never been paid, or if they have, only minimally.



They're trying to make some money by demanding taxes, fines, or bribes.



The UN are firm on this - they will not pay them.

In a country more than twice the size of New Zealand, there are only 400km of paved roads.



In the coming weeks Shearer and his staff will be scrambling to get food and supplies distributed.



A lot of this can be done by helicopter and plane, but some of the larger things - food, diesel and basic supplies - need to be taken in by road, or barge.

Two of the mission's operating areas are so inaccessible supplies are sent by barge up the Nile.



"It's a scramble to get food and healthcare into areas before the rainy season, and it's a constant battle to get from A to B."

SIEGFRIED MODOLA/REUTERS Displaced people receive food parcels at a joint UNICEF-WFP Rapid Response Mission in Nyanapol, northern South Sudan.

Shearer concedes it's one of the hardest assignments he's had yet - 65 aid workers have been killed, the economy is collapsing, inflation sits at 800 per cent, and there has been an outbreak of cholera.

He calls it the perfect storm of humanitarian operations.

Recently famine was declared in parts of South Sudan, the first declaration since Somalia, where more than quarter of a million people were estimated to have died between October 2010 and April 2012. Famine wasn't declared until 2011.

SIEGFRIED MODOLA/REUTERS Men unload boxes of nutritional supplements from an helicopter in Thonyor, Leer county, South Sudan.

In South Sudan, more than 100,000 people face starvation, the World Food Programme and other UN bodies say 1 million people are classified as being on the brink of famine, and another 5.5 million people need food aid.

Just last week under-secretary general for UN humanitarian affairs Stephen O'Brien also declared famine in Somalia, Nigeria and Yemen.

Across those four countries O'Brien said 20 million people faced starvation and $US4.4b is needed by July this year.



"People will simply starve to death" without coordinated efforts, he warned.



It's being called the worst humanitarian crisis since the UN was established at the end of World War II.

jJOK SOLOMON/REUTERS South Sudan's President Salva Kiir.

In this case, it takes a lot for a famine to be declared, according to UNICEF it's an extremely rare and very technical term.

The UN and other organisations define famine as when more than 30 per cent of children under age 5 suffer from acute malnutrition and mortality rates are two or more deaths per 10,000 people every day, among other criteria.



By the time famine was announced in Somalia in 2010, 100,000 people had already died.



What is different about South Sudan, says Shearer, is they already have rapid response teams and key systems in place for the people on the ground to deal with malnutrition in a conflict zone, unlike in Yemen.



In South Sudan, the next four months are crucial - April is planting season and harvest is between July and August.



If civilians can get through this safely, then some of these people will have food.

Shearer's role as head of the mission is as much strategic as it is political.



Within a week of arriving, Shearer was meeting with the leader of the South Sudanese Government, President Salva Kiir Mayardit, and former commander-in-chief of the Sudan People's Liberation Army.



"My job is to get the peace process back on track, which is frankly not going very well," says Shearer.



With lots of pockets of violence across the country, the Government is still set on winning militarily - peace talks aren't on their agenda.

SUPPLIED Labour leader David Shearer and wife Anuschka Meyer and daughter Anastasia in Jerusalem.

Last week Shearer was able to put a lid on tensions between two ethnic groups. He met with Governors and paramount chiefs on both sides who were positioning several thousand fighters to attack each other.

They agreed to pull back on a national day of prayer last week and will meet next week for ongoing peace talks.



Diffusing tensions like these literally saves thousands of lives.

Shearer has been working across the range of humanitarian organisations trying to broker putting peacekeeping troops in the middle of areas that are the worst hit by famine to try and create more security.



"It's satisfying to know you're making a difference - the difficulty is that half of my job - which is the peace process - just isn't firing as we'd hoped it would."



He's adamant that his ultimate success in the role will be determined by there no longer being a demand for his services.

"When I plead with the South Sudanese to make me unemployed - they laugh, and don't quite get it - but it's true - not being needed any more means I've done a remarkable job."

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