The U.S. Congress is expected to approve the proposed sale to South Korea of Global Hawk unmanned aerial vehicles, and the two sides are in talks on price, a government official said Friday.

South Korea hopes to purchase the advanced spy aircraft to bolster its surveillance capabilities over North Korea as the country prepares to retake wartime operational control of its troops from the United States in 2015.

Congress has the final say in the sale of Global Hawks to foreign countries.

“We expect the U.S. Congress will soon approve Global Hawk’s sale to South Korea,” a government official said on condition of anonymity. “But the price has risen too much and we’re in talks to pull it down.”

Defense Minister Kim Kwan-jin also told a parliamentary meeting Friday that the ministry’s efforts to bring in the spy aircraft are expected to “bear fruit soon,” adding that the country plans to hold negotiations to lower its price.

The price of each Global Hawk has jumped to 940 billion won ($846 million) from an initially estimated cost of some 400 billion won, sources said.

With the delay in the planned purchase of Global Hawks, South Korea has considered two other U.S.-made spy drones ― the Global Observer made by AeroVironment and Boeing’s Phantom Eye ― as alternatives. (Yonhap News)