Mattis warns North Korea on nukes

Secretary of Defense Mattis is on his first foreign trip. At a stop in South Korea, according to the AP, he tells the North to watch out:

America's commitments to defending our allies and to upholding our extended deterrence guarantees remain ironclad: 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.