A former U.S. ambassador to Seoul has advocated strengthening the U.S.’ extended deterrence to protect South Korea from North Korea’s nuclear and missile threats.

Harry Harris, former U.S. ambassador to Seoul and Commander of the U.S. Pacific Command, made the remarks during a virtual seminar hosted by the American Enterprise Institute on Monday.

Harris said that a loss of trust in the U.S. will prompt allies to build their own nuclear weapons, which they cannot be criticized for, stressing the importance of continuing to emphasize extended deterrence commitments to Japan, South Korea and Australia.

He also said the U.S. should strengthen its “nuclear triad” consisting of nuclear-capable bombers, submarines and intercontinental ballistic missiles.

In addition, Harris said that it would be a "mistake" to redeploy U.S. tactical nuclear arms to the Korean Peninsula despite the North Korean security challenge.

Regarding the North’s nuclear and missile capabilities, Harris assessed that Pyongyang is advancing both its strategic and ballistic missile capabilities and its evolving military threats have become far greater than before.