James DeHart of the State Department will lead the US delegation, the source said. Seoul officials said that South Korea is still carrying out internal procedures to pick its chief negotiator for the upcoming negotiations. 

The allies are bracing for what would be another grueling tug of war for the Special Measures Agreement, a defense cost-sharing deal, as the current deal, struck in February and valid only for one year, is set to expire on Dec. 31. 

Since 1991, Seoul has shouldered partial costs under the SMA -- for Korean civilians hired by the USFK, the construction of military facilities to maintain the allies' readiness and other forms of support. 

Under this year's 10th SMA, Seoul agreed to pay 1.04 trillion won ($873 million), an increase of 8.2 percent from the previous year.(Yonhap)