South Korea, the United States and Japan started two-day trilateral naval drills on Thursday in waters south of the Korean Peninsula as North Korea bristled at the exercise as a "reckless provocation."

The maneuvers off the southern island of Jeju are aimed at improving interoperability and communications between the navies of the three nations to facilitate cooperative disaster relief and maritime security activities, officials said.

The exercise is being staged beyond the territorial waters of any coastal nation, officials said.

Seoul's defense ministry officials declined to reveal how many military personnel or ships were mobilized for the trilateral exercise, which has been held since 2008.

The U.S. nuclear-powered aircraft carrier, the USS George Washington, will take part in the exercise Friday then will join a separate joint drill with South Korea set for Saturday through Monday, the U.S. Defense Department said in a statement.

On Thursday, North Korea's ruling party newspaper Rodong Sinmun denounced the three-nation exercise as a "reckless provocation."

"The dangerous moves to knock into shape the triangular military nexus is an act going against the trend of the times for regional peace and stability including the Korean Peninsula," it said.

"Dark clouds of a new war are thus hanging heavily in Northeast Asia including the peninsula," the newspaper said. (Yonhap News)