The sister of North Korean leader Kim Jong Un has warned that upcoming U.S.-South Korea military drills could jeopardize her country's talks with Seoul, raising doubts about a diplomatic breakthrough less than a week after both sides announced a resumption of communications.

Kim Yo Jong said Sunday that the plan to hold annual allied exercises this month "seriously undermines” efforts to restore ties, according to state-run Korean Central News Agency. The statement by Kim Yo Jong, one of the prominent faces of Pyongyang’s pressure campaign against Seoul and Washington, reinforces worries North Korea would use South Korean President Moon Jae-in’s desire for talks to try to force him to break with the U.S.

"Our government and army will closely follow whether the south Korean side stages hostile war exercises in August or makes other bold decision,” said the younger Kim, who’s a senior official with the ruling Workers’ Party of Korea. "Hope or despair? Choice is not made by us.”