There is a concern because the NCP is building up the military on the borders between the north and the south, especially in the area that has the oil and other interests that borders between the south and the north. Last month, during the visit of the Security Council to Juba, the President of the Government of Southern Sudan made an appeal officially to the Security Council to deploy forces between the borders of the north and the south.
On October 26th, 2010. See this statement in context.