South Sudan's president signed a peace deal on Wednesday to end a 20-month conflict with rebels, but he told regional African leaders at the ceremony that he still had "serious reservations".
President Salva Kiir, who has led South Sudan since it seceded from Sudan in 2011, last week asked for more time for consultations, drawing threats of U.N. sanctions if he failed to ink it within a two-week deadline.
"With all those reservations that we have, we will sign this document," he told African leaders gathered in Juba for the ceremony, speaking shortly before he signed.
Rebel leader Riek Machar, Kiir's long-time rival who is expected to become the country's First Vice President under the deal, signed the document last week in the Ethiopian capital.
U.N. chief Ban Ki-moon welcomed the signing of the peace deal, but his spokesman noted in a statement that it must be implemented.
"Now is the time to ensure that this agreement translates into an end to the violence, hardship and horrific human rights violations witnessed throughout this conflict," the statement said.
Thousands of people have been killed since the conflict erupted in December 2013 after a power struggle between Machar, an ethnic Nuer, and Kiir, from the dominant Dinka group. The fighting has increasingly followed ethnic lines, unsettling an already volatile region.
Many of the 11 million population have been driven to the brink of starvation and 2 million people have fled their homes, often to neighbouring states.
The deal follows months of on-off negotiations, hosted by Ethiopia, and several broken ceasefire agreements.
The rebels on Wednesday said that there had been other bout of fighting with government forces and they captured a town south of Juba after their troops were attacked.
But Kiir told the ceremony that the rebels had launched a raid in the north of the country earlier in the day.
"Now you can see who is for peace and who is for continued war," he said.
Kiir also gave a document to regional leaders listing his concerns. Mediators have said Kiir had voiced concerns about a demand that Juba become a demilitarised zone and conditions that he consult the first vice president on policy.
Machar, who was Kiir's deputy until he was sacked in 2013, has also conveyed doubts about aspects of power-sharing. Under the deal, he is expected to become Kiir's top deputy again.
Susan Rice, President Barack Obama's national security adviser, said the United States welcomed the deal as a "first step" toward ending the conflict, but that it would take "hard work" to implement the agreement.
"However, we do not recognise any reservations or addendums to that agreement", Rice said in a statement. "We will work with our international partners to sideline those who stand in the way of peace, drawing upon the full range of our multilateral and bilateral tools," Rice said.
U.S. State Department spokesman John Kirby went a step further, saying that if Kiir acted on his reservations and reneged on the deal the United States would support further U.N. sanctions, though he did not give specifics.
The United States had proposed a United Nations arms embargo and more sanctions from Sept. 6 unless the pact was signed by the 15-day deadline given to Kiir last week.
At the ceremony, Kiir said he had faced intimidation during the peace process and added negotiations were handled "carelessly" by regional and world leaders, saying a poor agreement could backfire on the region.
In comments echoed by Ugandan President Yoweri Museveni and Ethiopian Prime Minister Hailemariam Desalegn, Kenyan President Uhuru Kenyatta said it was a "happy day for us in the region" that the deal had been signed, and that South Sudan's leaders now need to focus on the future.