Sudan has declared a state of emergency as tensions mount along the disputed border it shares with its new neighbor, South Sudan.

As the AP reports, declaring a state of emergency gives the government expanded powers of arrest. On Saturday, Sudanese officials claimed they had arrested four people, including three foreigners.

Disputes over land in the oil-producing border area between the two countries have re-ignited hostilities in recent weeks. South Sudan split from Sudan in July 2011, but failed to resolve some critical issues before it gained its independence.

It's not just oil rights that haven't been established, as NPR's Ofeibea Quist-Arcton tells weekends on All Things Considered. It's also how revenues from that oil are shared, where exactly the border between the two nations is, and what rights citizens have. The current crisis is making one thing clear, however.

"It seems that oil has become the weapon of, if not war, certainly of conflict," Quist-Arcton says. Here's how she outlines what's behind the dispute:

"Most of the oil is now located in the South, but the North is saying that the South should pay much more for use of its pipeline that takes the crude oil for export down to Port Sudan at the Red Sea — which is in Sudan proper, in the northern part."South Sudan is saying, 'No, you are trying to cheat us. We are a new nation; we need this resource — that is how we are going to build our post-war country. And you are not going to blackmail us.'"

Both nations can ill-afford war. The countries are depleted after 50 years of violent conflict, first as a single-but-divided nation, then as two separate countries. The stakes are high; Sudan lost much of its economic force when it lost the oil fields that the previously united nation shared.

And yet both leaders have practically called their people to arms, Quist-Arcton reports. In the North, Sudanese President Omar al-Bashir says he is going to crush the "insects," as he calls the leadership in South Sudan.

Many people say they're prepared to fight if it comes to that, but many also say they cannot afford to.

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