Dec. 17 (GIN) – Leaders of the new nation of South Sudan are struggling to contain an uprising within the ruling party of President Salva Kiir, who tellingly has traded his ever-present fashionable cowboy hat for military fatigues.

Kiir rubbed his colleagues the wrong way when he sacked his entire cabinet including his vice president, Riek Machar, in July, suspecting him of plotting to take over the presidency. Mr Machar responded by calling the move a step toward dictatorship and declared his intention to challenge Mr Kiir for leadership of the party in the 2015 election.

The gap-toothed Mr Machar belongs to the Dok section of the Nuer people, South Sudan’s second largest ethnic group while President Kiir is from the Dinka clan.

Despite a pledge that the ruling SPLM party would never allow political power to be transferred through violence, Kiir took action against his perceived rivals this week and unleashed state forces in the capital city Juba. Kiir’s critics have been rounded up and gunfire is heard citywide. Some 13,000 people are seeking refuge at two U.N. bases in Juba. Hundreds are reportedly fleeing the city.

Former government ministers have been arrested but the whereabouts of Mr Machar are unclear.

To the rest of the world, business is booming in South Sudan. The burgeoning East African country is expected to have one of the world’s fastest growing economies. Its vast natural resources and urgent need for wide ranging investment attracted foreign investors to Juba last week for the country’s first major investment conference.

The positive outlook is based on oil exports and the economy’s vast potential to expand after decades of civil war and neglect.

But this week’s escalating problems are worrying the African country’s major ally. On Tuesday, Washington ordered U.S. citizens to leave South Sudan immediately. Special Envoy Donald Booth, in a Voice of America interview, said: “We’ve been concerned for some time of rising tensions. We’ve been reaching out to numerous parties to put together a picture of what has happened.”