A conflict on the Korean Peninsula would be "the worst kind of fighting" in most people's lifetimes, U.S. Defense Secretary Jim Mattis said in an interview aired on Sunday.

"We are working with the international community to deal with this issue," said Mattis in the interview with CBS News. "But the bottom line is it would be a catastrophic war if this turns into a combat if we're not able to resolve this situation through diplomatic means."

Calling the Democratic People's Republic of Korea (DPRK) a threat to Asian region, Mattis said the DPRK is also "a direct threat to the United States."

However, Mattis said that the administration of U.S. President Donald Trump does not draw red lines on the DPRK nuclear issue "unless we intend to carry them out."

"The President needs political maneuver room on this issue," said Mattis.

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 Koreaalso held their largest-ever joint military exercises in the past two months. At the end of April, the USS Carl Vinson nuclear aircraft carriertask 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."