Missile force of Korean People's Army attend a military parade in central Pyongyang, April 15, 2017. The Democratic People's Republic of Korea (DPRK) Saturday showcased its military muscles by parading all of its most-advanced ballistic and tactic missiles, including a submarine-launched ballistic missile which could strike targets 1000 km away. (Xinhua/Cheng Dayu)

WASHINGTON, May 19 (Xinhua) -- U.S. Defense Secretary Jim Mattis warned on Friday that military solution to the Democratic People's Republic of Korea (DPRK) nuclear issue would be "tragic on an unbelievable scale."

"So our effort is to work with the U.N., work with China, work with Japan, work with South Korea to try to find a way out of this situation," said Mattis here at a Pentagon briefing.

Tension has remained high on the Korean Peninsula over the past months between the United States and the DPRK over the U.S. threat to stage military attacks against Pyongyang in response to its nuclear and missile programs.

The United States and South Korea also held their largest-ever joint military exercises in the past two months. At the end of April, the USS Carl Vinson nuclear aircraft carrier task group arrived in the waters off the Korean Peninsula for a separate joint naval exercise with South Korea.

However, a joint statement by U.S. Secretary of State Rex Tillerson, Mattis and National Intelligence Director Dan Coats said last month that Trump aims to use economic sanctions and diplomatic measures to pressure the DPRK to dismantle its nuclear and missile programs.

The statement also said that the United States remained "open to negotiations" toward peaceful denuclearization of the Korean Peninsula while staying "prepared to defend ourselves and our allies."