British troops have arrived in South Sudan where they will be part of a UN peacekeeping mission, the Ministry of Defence has confirmed.
South Sudan, in north-eastern Africa, became the world's newest country in 2011 when it gained independence from Sudan after a long-running civil war.
However, there is ongoing fighting there between the government and rebel forces, which has killed thousands and displaced millions from their homes.
Up to 300 UK troops are to be sent.
The small military team, which is the first wave of troops from Britain, will join more than 12,000 UN troops from more than 50 nations currently stationed in the country.
The UK personnel will be split into two engineer squadrons to provide "vital engineering work to strengthen infrastructure as well as further advisory support", the MoD said.
There will be further deployments throughout the rest of 2016, it added.
Defence Secretary Michael Fallon said: "The arrival of British personnel clearly demonstrates our commitment to supporting UN efforts to improve conditions in some of the world's most destabilising conflicts."
Britain has long been a large financial contributor to UN peacekeeping missions and is the fifth highest provider of funds.
But its troop commitment has been relatively small - focused mainly on 250 soldiers based in Cyprus who wear the distinctive blue berets of the UN.
Prime Minister David Cameron announced last year the UK would double its contribution to active peacekeeping in 2016, with the deployment of British troops to South Sudan, as well as a team of 70 UK personnel to Somalia.
The first British troops arrived in Somalia last month.
It was in the UK's interests to "step up" in supporting both missions because it would lead to "less terrorism, less migration, less piracy", Mr Cameron said.
British troops would not be involved in combat roles, he added.
After decades of fighting in the region that is now South Sudan, both sides signed a peace deal last August.
However, fighting has continued, and an estimated 1.7 million people are displaced from their homes, according to the UN's latest figures.
Since the UN's South Sudan mission started in 2011, 17 peacekeeping troops have been killed.