The study is not the first to highlight such concerns. A commission formed by Congress to analyze the policy document that guides U.S. national security thinking and operations concluded in November that the U.S. is no longer clearly superior to the threats it faces around the world and that it would struggle to win wars against China or Russia.

"U.S. military superiority is no longer assured and the implications for American interests and American security are severe," the National Defense Strategy Commission wrote in its findings at the time. It attributed the weakened defense infrastructure to "political dysfunction and decisions made by both major parties."

China, meanwhile, has found efficient ways to counter or exploit U.S. military weaknesses. Its decision to reform its coast guard as a military service last year raised sharp concern among Pentagon leaders, concerned about the unclear boundary between China's foreign military operations and other encounters – such as its annexation of islands and reefs in international waters – that Beijing could frame as a domestic dispute.

China has also expanded its soft power influence in the region, investing heavily in small countries around the Pacific Rim, such as Micronesia and Vanuatu, that the U.S. and partner countries consider a pincer movement around territory Beijing wishes to control.