Secretary of Defense, James Mattis, made a clear statement regarding North Korea’s nuclear missile program on Friday, while continuing his visit in the South Korean capital, Seoul.

Mattis explained in no uncertain terms that the use of nuclear weapons by North Korea against the United States or any of its allies would be met with an “effective and overwhelming” response.

The United States has long considered both South Korea and Japan to be beneath the American “nuclear umbrella,” or portions of the world that, if under nuclear attack, would be met with the same nuclear response an attack on the United States itself would warrant.  However, Mattis’ decision to address North Korea directly during a visit to the South Korean capital marks a slight departure from the norm, as such declarations are usually made in a more nuanced manner.

“North Korea continues to launch missiles, develop its nuclear weapons program, and engage in threatening rhetoric and behavior,” Mattis said during a public meeting with his South Korean counterpart, Defense Minister Han Min Koo.