WASHINGTON — The commander of the U.S. Indo-Pacific Command is expected to speak with his Chinese counterpart as early as Monday, according to three U.S. officials familiar with the planning, as the two superpowers try to rebuild military ties in an effort to avoid conflict.

Adm. Samuel Paparo is expected to speak with Gen. Wu Yanan, the commander of China’s Southern Theater, which is responsible for Beijing’s vast claims over the South China Sea. The call will mark the first time in…