South Korea and the United States have made progress in negotiations on sharing defense costs, but have yet to reach a final agreement.

A Foreign Ministry official familiar with the negotiations told a media briefing Monday that the two sides worked hard to narrow differences during the ninth round of cost sharing talks held in Hawaii last week.

The official said the allies agreed to exert best efforts to reach a deal at the earliest date within the year to ensure a stable environment for U.S. troops stationed in South Korea.

The source said a considerable portion of the agreement's wording is completed, but more coordination is necessary to agree on the sticking point of Seoul's contribution.

The current Special Measures Agreement, which sets the amount of Seoul's cost of stationing U.S. troops in the country, is to expire at the end of the year.