South Sudan President Salva Kiir was meeting again with rival Riek Machar on Monday in neighbouring Sudan amid fragile efforts to end their country's five-year civil war.The meeting mediated by Sudan's President Omar al-Bashir in Khartoum resulted in "some points that enable South Sudan's people to enjoy peace," Sudan's state-run news agency SUNA quoted Uganda's President Yoweri Museveni as saying. It did not give details.Kiir and Machar met face-to-face last week for the first time in nearly two years in neighbouring Ethiopia, but South Sudan's government rejected the idea of Machar returning again as Kiir's deputy. The East African regional bloc's leaders later said Machar could leave house arrest in South Africa but was not welcome in any member country except to participate in peace talks.Tens of thousands of people have been killed in South Sudan's civil war, which has created Africa's largest refugee crisis since the 1994 Rwandan genocide and left millions near famine. A power-sharing peace attempt failed when Machar fled his vice president post, and the country, amid fresh fighting in the capital, Juba, in July 2016.Kenya is expected to host another round of talks between the rivals in the weeks ahead.The United States, the top humanitarian donor to South Sudan, has expressed growing impatience with the warring sides, sponsoring a resolution adopted by the UN Security Council early this month that threatens an arms embargo on South Sudan and sanctions against six people, including the country's chief of defence, if fighting doesn't stop and a political agreement reached.The new US ambassador to South Sudan told The Associated Press in an interview on Monday that the US is skeptical of the latest peace talks."If it's just a repeat of the failed 2015 agreement (that returned Machar to his role as Kiir's deputy) it's not going to work," Ambassador Thomas Hushek said.The ambassador called the closed-door session between Kiir and Machar last week in Ethiopia a "very backwards step" in terms of inclusivity.Hushek also cited concerns over the "lack of outcome" and the lack of action by heads of state and government in the regional bloc leading the talks, the Intergovernmental Authority on Development, on punitive measures against those who violated the latest cease-fire in December.South Sudan's government on Monday said Kiir should be applauded for meeting with Machar.Meanwhile, the armed opposition said fighting continued."The regime in Juba should refrain from the negative thinking of continuing with war and accept peace to come politically," spokesman Lam Paul Gabriel said in a statement.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.