South Sudan's 1st birthday clouded by tensions

South Sudan, the world's newest nation, turned one year old on Monday, but its anniversary comes amid high tensions with its northern neighbor and economic concerns.

With its capital in Juba, South Sudan became independent last year following decades of civil war. Its arrival in the international community was celebrated at the time, but conflict with the Sudanese regime soon resumed.

Border clashes have brought the countries to the brink of war and left South Sudan coping with a massive humanitarian crisis as people flee the fighting.

The South Sudan state of Upper Nile has been flooded with refugees crossing the border from Sudan. In total, aid agencies estimate that at least 150,000 refugees from Sudan are currently in South Sudan.

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The humanitarian problems have coincided with economic woes.

The South Sudanese government lost 98 percent of its revenue when it halted oil production amid a dispute over transportation and processing fees with Sudan.

South Sudan obtained around 70% of the formerly united country's oil reserves when it became independent last year. But the countries have been unable to agree on how much the landlocked South should pay to use infrastructure that remains in Sudan.

South Sudan shut down production in late January after accusing Sudan of stealing $815 million worth of its oil. Sudan said it confiscated the crude to make up for unpaid fees.

The shutdown has sent the economies of both countries reeling, but South Sudan has been hit particularly hard by the loss of income from virtually its only export.

The young nation has also wrestled with corruption in its first year.

In May, South Sudan's president wrote to more than 75 government officials and eight foreign governments in an attempt to recover $4 billion lost through corruption.