NEW YORK -- The U.S., South Korea, Japan and China have all been ratcheting up the pressure on North Korea over its threats and bombast surrounding its nuclear program.

“CBS Evening News” anchor Scott Pelley spoke with Chris Hill, a former U.S. ambassador to South Korea in the George W. Bush administration. Hill led the U.S. delegation in 2005 talks with North Korea over curtailing its nuclear program.

He says that North Korea is a threat to American lives.

“We have 28 to 30,000 Americans in South Korea. We have to understand this is an agreement we have we are duty-bound, treaty-bound to come to South Korea’s defense should the North Koreans attack,” Hill said.

“If we have to go in there ... we would be in the middle of a fight, so you bet it’s a threat to our lives.”

Watch the video above for an extended clip of Pelley’s interview with Hill, including his assessment of Kim Jong Un’s sanity and whether President Trump’s White House is ready to handle the issue.