A former U.S. ambassador to South Korea says he once suggested that Kim Jong Un be invited to the United States for an "orientation trip" when Kim's father was still in charge of North Korea, but the idea was rejected — which he calls a mistake.

Donald Gregg spoke to reporters Friday about his new memoir.

Gregg says he wrote to Vice President Joe Biden when Biden was still in the Senate and said the young Kim should be invited because Kim was educated abroad, spoke some English and would be around for decades.

But Gregg says the idea was brushed aside, "so we missed doing something."

Gregg led the Korean Society at the time. He criticizes how presidents Barack Obama and George W. Bush have handled North Korea.