China is modernizing its nuclear forces and trying to assert dominance in the East and South China Seas, tensions are continuing between North and South Korea, and Russia needs to be watched in the Pacific.

That was the regional environment described by Adm. Cecil Haney, head of U.S. Strategic Command, at a change of command Thursday for a key component in the U.S. defense strategy: the U.S. Pacific Fleet submarine force headquartered at Pearl Harbor.

After two years on the job, Rear Adm. Phillip G. Sawyer turned over the sub force to Rear Adm. Fritz Roegge in a ceremony at Pearl Harbor’s Sharkey Theater, but Sawyer is remaining in Hawaii as deputy commander of U.S. Pacific Fleet.

“The reach and endurance of our submarine force as part of our whole-of-government re-balance to Asia-Pacific is vital to regional stability, maritime security, the world’s economic engine and assuring our allies, both in and beyond this region,” Haney said.

Haney told those assembled he just wants more of them — a task made difficult in a time of defense budget cuts.

“We must, for example, have more of these new Virginia-class (attack) submarines,” Haney said. “We must also recapitalize our sea-based strategic deterrent. Our Ohio-class submarines have been sustained beyond their original 30-year service life” to 42 years.

The Pacific sub force also acts as Task Force 134 on behalf of Strategic Command for nuclear deterrence, and as Task Force 34 for theater anti-submarine warfare.

The Navy lists as part of the Pacific Fleet 42 submarines in the region, with 20 attack subs at Pearl Harbor; eight ballistic missile subs, two guided missile subs and three attack subs in Bangor, Wash.; five attack submarines in San Diego; and four attack subs in Guam.

The sub force said it provides anti-submarine warfare; anti-surface ship warfare; precision land strikes with Tomahawk missiles; intelligence, surveillance and reconnaissance; and early warning and special warfare capabilities to U.S. Pacific Command, and strategic deterrence for Strategic Command.

Sawyer assumed command in August 2013 and ran the daily business of 60 percent of the U.S. submarine force, the Navy said. That included overseeing the deployment of 42 submarines through 29 attack and guided-missile missions, as well as 40 nuclear deterrence patrols.

Sawyer is a “stellar flag officer. He’s done remarkable work,” Haney said. He directed numerous high-priority missions delivering intelligence to national security leadership — “stuff I can’t discuss in this program,” Haney added.

A submarine arms race is occurring in the Asia-Indo-Pacific region, meanwhile, with the stealthy undersea vessels able to provide an unseen measure of protection in increasingly vital sea lanes.

“We see China’s efforts to assert regional dominance in the East and South China Seas” while also operating a new ballistic missile submarine force and modernizing its mobile intercontinental ballistic missiles, Haney said.

A July 28 Congressional Research Service report on China’s naval modernization said the country’s improving capabilities are seen as “posing a potential challenge in the western Pacific to the U.S. Navy’s ability to achieve and maintain control of blue-water ocean areas in wartime — the first such challenge the U.S. Navy has faced since the end of the Cold War.”

Roegge, an honors graduate from the University of Minnesota commissioned through the ROTC, most recently served as director of the military personnel plans and policy division at the office of the Chief of Naval Operations in Washington, D.C.

Roegge said it’s “an exciting time to be a submariner. The nation has important work for us to do, and what you do is the stuff that people make movies and write books about.”