SEOUL, Nov. 19 (Xinhua) -- South Korea and the United States on Tuesday ended their negotiations in Seoul on how to share upkeep costs for the U.S. Forces Korea (USFK) without progress, according to South Korean foreign ministry.

The ministry said in a statement that the 11th Special Measures Agreement (SMA) negotiations failed to go on "as scheduled." The SMA is a South Korea-U.S. pact to share defense cost for about 28,500 U.S. troops stationed here.

The negotiations were originally scheduled to last for two days through Tuesday, but it was cut short in differences over the upkeep cost burdened by the South Korean side.

The statement noted that the U.S. side held a position that the South Korean share of the upkeep cost should be increased drastically by setting a new article in the SMA, while Seoul maintained that the increase should be within the mutually acceptable range under the SMA framework that the two sides had agreed upon for the past 28 years.

It said South Korea will make utmost efforts to ensure that the country will take a fair share of the defense cost at a reasonable level that contributes to strengthening the South Korea-U.S. alliance and the combined defense posture.

Jeong Eun-bo, South Korea's chief negotiator, told a press conference in Seoul that there was a significant difference between the U.S. proposal and the South Korean principle in negotiations.

He vowed to make efforts with patience to reach a deal that can be acceptable to both sides.

The United States reportedly demanded around 5 billion U.S. dollars from South Korea for next year's upkeep cost for U.S. soldiers here. South Korea agreed to pay about 870 million U.S. dollars this year.

The 10th SMA, which was reached in March, was set to expire by the end of this year. Since 1991, South Korea has shared the defense cost for U.S. forces here, including costs for South Korean civilians hired by the USFK, for construction of military facilities and for logistics support.