This week, China announced that it was sending 700 military personnel to join the UN's peacekeeping mission in South Sudan, an oil-rich east African state and site of an ongoing civil war. China has contributed to UN peacekeeping missions before, but the unprecedented size of its contribution, and its purpose in sending troops, reveals just how complicated China's foreign outreach has become as the country continues its rise to super-power status.

As the Wall Street Journal reported, China is deploying troops in order "to help guard the country's embattled oil fields and protect Chinese workers and installations," according to a spokesman for South Sudan's president. China is largely acting to protect its own interests here, rather than regional or international peace.

South Sudan took most of the former Republic of Sudan's oil with it when it was allowed to secede from Khartoum in 2011, bringing a final resolution to decades of civil war and creating the newest country on earth. In 2011, when Sudan was still a single country, it accounted for 5% of China's oil imports. But most of Sudan's oil was in areas that were now a part of an independent South Sudan, where China's policies in the region — which included support for the oppressive Khartoum government that fought the south during a long civil war — made it none too popular.

But independence has reshuffled the relationship between Juba and Beijing, and oil is a large part of the reason why.

Origins of Chinese oil imports in 2013, by percentage U.S. Energy Information Administration A dispute with Khartoum over the sharing of southern oil revenues resulted in the suspension of South Sudan's entire oil industry in 2011; Chinese imports of Sudanese oil totally halted in much of 2012 and 2013. When South Sudan's oil came back online in 2013, the economically hobbled country wasn't in a position to turn away potential customers, just as a growing China wasn't in a position to alienate potential sources of oil.

Relations improved, and China, which held a 40% stake in the united Sudan's state oil company before the country's breakup, became the major investor in South Sudan's oil infrastructure. Beijing continued to hold 40% of a joint partnership to explore and develop South Sudan's oil resources.

Then civil war broke out in December of 2013. The rebels managed to threaten not just South Sudan's oil wells, but the integrity of the region's only pipeline as well.

The South Sudan turmoil comes within a larger context of Chinese investment in Africa, where it's spent substantial political and economic capital in recent decades. This has allowed Beijing to project its soft power through an emerging region while obtianing access to vital resources and markets — Angola, for instance, was China's second-largest oil supplier in 2013.

But China's Africa policies have also had some blowback. As Howard French recounts in his recent book China's Second Continent: How A Million Migrants Are Building A New Empire In Africa, Chinese overtures in the continent can have an imperialist flavor to them, with Beijing following policies that jeopardize national sovereignty and crowd out local labor and industry.

With many Africans skeptical of China's intentions and impact on their continent, Beijing can't simply send its own troops to protect its investments and citizens when they're in danger, as they currently are in South Sudan. After 20 years of attempting to cultivate Africa as a sphere of influence, China understands that a softer touch is needed — even in situations that might require the use of force.

The UN gives them a way out of this dilemma, at least in this case.

The UN has a peacekeeping force in South Sudan. This week's announcement means that China is contributing troops to the mission, where they'll fight under the iconic "blue helmet" worn by all UN peacekeepers.

As a troop contributor, China's participation is contingent upon what it's willing to let its military do during a peacekeeping deployment — and the UN typically doesn't turn a country down when it volunteers its troops for a mission. After all, peacekeeping missions are contingent upon member states volunteering their forces.

So China is effectively using the UN as cover for a military deployment that serves Beijing's specific interests.

It's another sign that China's engagement with the rest of the world is getting more complex as its economic and political power grows — and that the planet's rising superpower is becoming increasingly sophisticated in how it defends its interests.