U.S.-China Strategic Competition in South and East China Seas: Background and Issues for Congress [Updated September 24, 2019] [open pdf - 2MB]
From the Summary: "In an international security environment described as one of renewed great power competition, the South China Sea (SCS) has emerged as an arena of U.S.-China strategic competition. U.S.-China strategic competition in the SCS forms an element of the Trump Administration's more confrontational overall approach toward China, and of the Administration's efforts for promoting its construct for the Indo-Pacific region, called the Free and Open Indo-Pacific (FOIP). China's actions in the SCS in recent years--including extensive island-building and base-construction activities at sites that it occupies in the Spratly Islands, as well as actions by its maritime forces to assert China's claims against competing claims by regional neighbors such as the Philippines and Vietnam--have heightened concerns among U.S. observers that China is gaining effective control of the SCS, an area of strategic, political, and economic importance to the United States and its allies and partners."
CRS Report for Congress, R42784
Congressional Research Service: https://crsreports.congress.gov/