The U.S. wants South Korea to eventually deploy its newly approved nuclear-powered submarines to help counter China’s rapidly expanding fleet, calling it a responsibility expected of a key ally, according to a top U.S. admiral.

"Utilization of that submarine for countering China, I think is a natural expectation with that type of capability,” Adm. Daryl Caudle, chief of U.S. naval operations, said in Seoul on Friday. He spoke hours after both nations released a fact sheet that put in writing U.S. consent for South Korea to build nuclear-powered submarines.

"I think there will be a responsibility for Korea to deploy those submarines globally and move away from just being a regional navy to a global navy,” Caudle said.