Defense Secretary James Mattis has tapped Admiral Phil Davidson, a four star admiral with expertise in anti-submarine and electronic warfare, to take command of the U.S. Navy’s troubled Pacific Fleet. With what some have characterized as a “grueling” operational tempo and a rash of tragic and embarrassing incidents involving surface vessels in the Pacific over the last year, Davidson faces a complex set of challenges.

As the Pacific Fleet commander, Davidson will have to find a way to manage a cultural shift within his fleet, while participating in force wide readiness and modernization efforts and continuing to serve as America’s “big stick” in what is perhaps the most contested waterway on the planet. However, according to Davidon’s own testimony at his nomination hearing before the Senate Committee on Armed Forces last week, those challenges are just the beginning.

Davidson’s expertise regarding submarine warfare was display during the hearing, as he laid out a troubling forecast of Chinese military expansion throughout the Pacific, and particularly in the South China Sea. In recent years, China has rapidly expanded their ship-building infrastructure, launching more than twenty new warships since 2016 and quickly moving toward launching two additional aircraft carriers. However, according to Davidson, the most troubling advancements China’s navy has been making have been beneath the surface.

The United States maintains a significant asymmetric advantage in undersea warfare, but the [People’s Liberation Army] is making progress. China has identified undersea warfare as a priority, both for increasing their own capabilities as well as challenging ours.” Davidson told lawmakers.