By Ishbel Matheson
BBC, Nairobi, Kenya
The Sudanese peace talks which have been continuing in Kenya are reported to have run into difficulties over the security arrangements to be put in place during a post-war transitional period.
The big issue is whether Sudan should have one army or two.
The negotiations between the rebel leader, John Garang, and the Sudanese Vice-President, Ali Osman Taha, are seen as critical for the survival of the peace process.
The talks are taking place amid the quiet acacia glades of Lake Naivasha in the Rift Valley region.
The fact that Mr Garang and Mr Taha have been talking now for a week has been taken as an optimistic sign.
But the arrival of another delegation from Khartoum, headed by the minister of defence, seems to have complicated matters.
There are reported to be difficulties over the security arrangements put in place during the crucial six-year transitional period.
At issue is whether Sudan should have one army or two.
The rebels say two forces are needed, believing the SPLA should still largely control the south.
The government team now seems to be disputing this arrangement.
This is a fundamental and extremely difficult issue which goes to the heart of the two-decades war in Sudan - all the more so because, as the chief negotiator in Kenya has made plain, if these talks fail, Sudan should brace itself for another outbreak of war.