South Korea and the US failed to close negotiations on how to share the costs for the stationing of American troops here, an official said Friday, with the allies still at loggerheads on the total amount of money Seoul has to pay.

South Korean negotiator Chang Won-sam and his US counterpart Timothy Betts held the 10th round of meetings from Tuesday to Thursday in Seoul on the renewal of the Special Measures Agreement that is set to expire Dec. 31.

Under the current SMA, a five-year contract between the US and South Korea, South Korea pays about 960 billion won ($848.8 million) per year for the stationing of more than 28,500 American troops here.

“Apart from one or two focal points, including the total amount, we reached agreements on every issue and drafted a document. But the final deal was not made due to differences on the total amount,” said an official from the Foreign Ministry on condition of anonymity.

The two countries are unlikely to seal a deal before the end of the year. In this case, the agreement from this year will be extended and the difference in the amount will be covered by a reserve fund, according to the official.

Seoul and Washington have held a total of 10 rounds of talks since they began a new round of negotiations in March.

They have negotiated how much South Korea will pay for the stationing of the USFK; how long the agreement will be valid; how sharply costs will increase every year; and whether Seoul will financially support Washington’s deployment of strategic assets here.