South Korea and the United States failed Thursday to narrow differences over the sharing of the cost for stationing American troops here as Seoul rebutted Washington’s call for additional financial backing, a government source said. During their latest two-day meeting in Seoul, the allies were split over how much each side would contribute to the cost of maintaining the 28,500 US troops here for the period of 2014-18, said the source at Seoul’s foreign ministry. The countries may meet again in late August possibly in Seoul to resume their negotiations as both sides hope to wrap up the negotiations by October, according to the source. Both countries first signed the Special Measure Agreement (SMA) in 1991, setting up legal grounds for South Korea to help finance the United States Forces Korea, according to (Yonhap) news agency. Under the latest SMA renewed in 2008, South Korea agreed to pay 4.07 trillion won (US$3.6 billion) for the five-year period ending in 2013. In 2013 alone, the South paid 869.5 billion won, which accounted for more than 40% of the USFK defense costs. The US troops are stationed in South Korea under a mutual defense treaty aimed at deterring potential aggression from North Korea.