James Wani Igga, vice president of South Sudan, speaks during the 70th session of the United Nations General Assembly at U.N. headquarters on Thursday. (Julie Jacobson/Associated Press)

THE SEEMINGLY endless perils of South Sudan appeared to finally reach a promising turning point with the signing of a cease-fire in August, to be followed by a serious plan for a transition to power-sharing by the warring parties. But judging by recent events, the conflict is still raw and prospects for a permanent peace remain tenuous. Since fighting broke out in December 2013, tens of thousands have been killed. The two prominent figures in South Sudan, President Salva Kiir and rebel leader Riek Machar, are still at the brink, spitting nails at each other over a chasm of mistrust. The United States and others who have labored so long for South Sudan, only to see it plunge into a devastating civil war, must not abandon the people of this nation and must pressure the leaders to overcome their mistrust for a lasting settlement.

The latest sign of danger came last week, when Mr. Kiir announced, unilaterally, a plan to change the political map of the country from 10 states to 28. The British had once established 21 colonial districts, and the rebels had suggested returning to this formula during an earlier negotiation, but the plan was brushed off by the government. Rather suddenly on Oct. 2, Mr. Kiir signed a decree creating 28 states without consulting Mr. Machar.

Mr. Kiir’s vice president, James Wani Igga, told us in an interview this week that the plan was put forth “in good faith” to achieve a much-needed devolution of power to local governments. But Mr. Machar is worried that his rival has cleverly found a way to dilute Mr. Machar’s power in some key states. Mr. Machar has called a meeting of his 120-member leadership council for Oct. 20, and he told us separately the plan “definitely would” kill the peace deal if not amended. Mr. Igga insisted that the power ratio wouldn’t change, but the reaction of the rebels underscores the deficit of trust. Mr. Kiir has repeatedly expressed “reservations” about the peace deal, and the latest move hardly suggests willingness to share power. The United States, Norway and the United Kingdom, which have played a role in the negotiations, declared in a statement Oct. 6 that the plan for 28 states “directly contradicts” the peace deal Mr. Kiir signed in August. Mr. Kiir should shelve it.

There are many other looming problems. Both sides failed to agree on terms for demilitarization of Juba, the capital, a sensitive issue. Fighting continues to flare up, most recently last week in Unity State. The International Committee of the Red Cross and Doctors Without Borders report their aid efforts have been disrupted by fighting there.

Both sides need to do more to stop these flare-ups, resolve the Juba troops issue and implement the peace accords. There also must be a reckoning for the human rights atrocities of the civil war. An African Union commission of inquiry has completed a report, expected to be made public soon, documenting abuses by both sides. Neither can now flinch from bringing to justice those fighters and commanders who are responsible.