US warns North Korea of 'overwhelming' response if nuclear arms used
North Korean leader Kim Jong Un gives field guidance to Pyongyang Orphans' Primary School, in this undated photo released by North Korea's Korean Central News Agency (KCNA) February 2, 2017. KCNA via REUTERS

U.S. President Donald Trump's defense secretary warned North Korea on Friday of an "effective and overwhelming" response if Pyongyang chose to use nuclear weapons, as he reassured Seoul of steadfast U.S. support at the end of a two-day visit.

"Any attack on the United States, or our allies, will be defeated, and any use of nuclear weapons would be met with a response that would be effective and overwhelming," Defense Secretary Jim Mattis said, speaking at South Korea's defense ministry.

(Reporting by Phil Stewart; Editing by Richard Pullin)