South Sudan President Salva Kiir signed a peace accord Wednesday to end 20 months of civil war, but also issued a list of "serious reservations", warning the deal might not last.
"The current peace we are signing today has so many things we have to reject," Kiir said at a ceremony, witnessed by regional leaders, diplomats and journalists.
"Such reservations, if ignored, would not be in the interests of just and lasting peace."
At least seven ceasefires have already been agreed and then shattered within days -- if not hours -- in the world's newest country, which broke away from Sudan in 2011.
The deal was signed as the country faced threats of United Nations sanctions, and Kiir criticised what he called "intimidating messages" which he suggested were aimed at "regime change", without giving further details.
Although a list of his concerns was handed out, the deal was welcomed by regional leaders, including Ugandan President Yoweri Museveni, who had sent in troops to back Kiir's forces.
Under the deal, they now have 45 days to leave.
"This was not a just war, it was an unjust war. It was a wrong war, at a wrong place, at a wrong time - and the sooner you finish it the better," Museveni said.
"You need to get out of this trap, remove the guns, give back power to the people," he added.
Tens of thousands of people are believed to have died in the nearly two-year long war, marked by ethnic massacres and rape.
"This is the day the people of South Sudan have been waiting for 20-months," said Ethiopian Prime Minister Hailemariam Desalegn, who has hosted months of talks aimed at ending the war.
"We must all accept that we need to give and take... it is better for us to find solution around the negotiation table," Kenyan President Uhuru Kenyatta said.
"Look at the greater picture... the need for peace, the need for unity."
Kiir also accused rebel forces of attacks on Wednesday, saying it showed the deal signed earlier by rebel chief Riek Machar was not being respected.
"It is showing that what we are doing here is not accepted by the other side," Kiir said, adding he believed that negotiations on the deal should continue.
"It is not a Bible, it not the Koran, why should it not be revisited?" Kiir said.
"Let us give ourselves time and see how we can correct these things," he added.