BEIJING—China outlined plans to shift its armed forces’ focus toward maritime warfare and accused foreign countries of “meddling” in the South China Sea, setting the stage for a confrontation between senior U.S. and Chinese defense officials at a security conference this weekend.

In its first public summary of military strategy, the State Council—China’s cabinet—said the navy will expand its operations from offshore areas to the open seas, while the air force will shift its focus to include offensive operations as well as defense of China’s territory.

The changes were designed to tackle new security challenges, including the U.S. shift of military and other resources to Asia, Japan’s efforts to overhaul its defense policy, and “provocative actions” from neighboring countries in the South China Sea, the State Council said in a white paper on military strategy published Tuesday.

… “This document lays down a marker ahead of the Shangri-La Dialogue,” setting out China’s likely talking points at the annual gathering of top defense officials, said Richard Bitzinger, a senior fellow at the S. Rajaratnam School of International Studies in Singapore.

Although the white paper mainly reiterates China’s efforts to modernize its armed forces, “it’s the first time that they’ve laid out their military strategy in an organized, cogent fashion,” Mr. Bitzinger said.