China declined a U.S. request for the countries’ defense chiefs to meet this week, following concerns Beijing raised over sanctions Washington imposed on its top general.

While the rejection is latest rebuff of U.S. efforts to strengthen military communications, it appears to be a setback for White House efforts to restore ties with key officials amid heightened tensions.

The U.S. had proposed in May that Secretary of Defense Lloyd Austin meet his counterpart, Li Shangfu, in Singapore during the Shangri-La Dialogue, a marquee Asia-Pacific security gathering.