South Sudan's warring factions may face further international pressure if they do not reach a peace deal by Aug. 17, US President Barack Obama said on Monday, convening east African leaders for urgent talks in neighbouring Ethiopia. Options discussed by those leaders ranged from applying new sanctions to sending in a "regional intervention force," a US official told reporters after the meeting. Obama, who is in Ethiopia on a two-nation Africa tour, convened the talks in Addis Ababa to discuss the conflict raging between President Salva Kiir's government and rebels commanded by Riek Machar. The group of leaders from Kenya, Ethiopia, Uganda, Sudan and the African Union agreed on the urgency of the situation but did not reach a consensus on what to do if the deadline comes and goes as others have done, the US official said. "If we don't see a breakthrough by the 17th, then we have to consider what other tools we have to apply greater pressure on the parties," Obama told a news conference with Ethiopian Prime Minister Hailemariam Desalegn, who has hosted peace talks. "The possibilities of renewed conflict in a region that has been torn by conflict for so long, and has resulted in so many deaths, is something that requires urgent attention from all of us," Obama said. "We don't have a lot of time to wait." The South Sudanese government responded by saying additional sanctions could harm the peace process. Ateny Wek Ateny, a spokesman for Kiir, told Reuters: "What we need from the international community is support, so if more measures come it will jeopardise the chances of the people of South Sudan". Rebel spokesman James Gatdet welcomed Obama's comments and urged the government to tackle key obstacles, saying "peace is possible". The option of a regional force was not proposed by the United States, according to Obama administration officials who said such a force could be used to implement a peace deal if one were reached. The United States and the European Union have already imposed sanctions on individual commanders from both sides. They could increase those sanctions with or separately from partner countries in the region. ‘Strong signal' Thousands have been killed and more than 2.2 million displaced since fighting broke out in December 2013. Both sides have been accused of human rights abuses and indiscriminate killings, which have often been carried out along ethnic lines, with Machar's Nuers pitted against Kiir's powerful Dinkas. Hailemariam said Monday's meeting should send a "strong signal". "The people are suffering on the ground and we cannot let this go on," he said. The regional grouping IGAD, which includes Ethiopia and has been mediating, has threatened sanctions in the past, but more recently said they would not help. Its proposal for a power-sharing agreement was rejected in June by South Sudan's opposition. Speaking to FRANCE 24, Machar described the latest peace proposal as "deeply flawed". "I want an agreement on a system of governance that will make South Sudan stable [...] and address the divisions of the people of South Sudan," he said. Western diplomats have pushed countries in the region to put more pressure on the South Sudanese to make peace. The United States, Britain and Norway were among the main Western states that sponsored South Sudan when it seceded from Sudan in 2011. Those at the talks included Ugandan President Yoweri Museveni, Kenyan President Uhuru Kenyatta, Sudanese Foreign Minister Ibarahim Ghandour and the chair of the African Union Commission, Nkosazana Dlamini-Zuma.