"I'm delighted to be home," he said. "It's been a great homecoming. I'm tired, but ready to be with my family."
He also thanked the Swedish Embassy in Pyongyang, North Korea, and the U.S. Embassy in Beijing for helping to secure his release.
Newman was detained in late October at the end of a 10-day trip to North Korea, a visit that came six decades after he oversaw a group of South Korean wartime guerrillas during the 1950-53 war.
Last month, Newman read from an awkwardly worded alleged confession that apologized for, among other things, killing North Koreans during the war. Analysts questioned whether the statement was coerced, and former South Korean guerrillas who had worked with Newman and fought behind enemy lines during the war disputed some of the details.
North Korea cited Newman's age and medical condition in allowing him to leave the country.
Rep. Adam Schiff, a Democrat whose district encompasses Newman's Palo Alto home, said on CNN Sunday morning that North Korea's reason for detaining Newman may never be completely explained. He said North Korea's internal politics, the country's desire for global attention and other wants could have prompted Newman's detention.
"They often will grab people to gain attention to get a world leader come and rescue them from North Korea," Schiff said. "It may be a shout to the rest of the world that we want you to pay attention to us again and our nuclear program or it may be simply confined to something Mr. Newman said that caused him to be taken off the plane."
Barbara Ingram, a friend and neighbor of Newman's at the senior citizen complex where they live said residents broke into applause when news of Newman's release was announced Friday during lunch.
"A great cheer went up," Ingram said. "We are all so very relieved and grateful."
Newman's detention highlighted the extreme sensitivity with which Pyongyang views the war, which ended without a formal peace treaty, leaving the Korean Peninsula still technically in a state of war. The conflict is a regular focus of North Korean propaganda and media, which accuse Pyongyang's wartime enemies Washington and Seoul of carrying on the fighting by continuing to push for the North's overthrow.
The televised statement read last month by Newman said he was attempting to meet surviving guerrilla fighters he had trained during the conflict so he could reconnect them with their wartime colleagues living in South Korea and that he had criticized the North during his recent trip.
Members of the former South Korean guerrilla group said in an interview last week with The Associated Press that Newman was their adviser. Some have expressed surprise that Newman would take the risk of visiting North Korea given his association with their group, which is still remembered with keen hatred in the North. Others were amazed that Pyongyang still considered Newman a threat.
"As you can imagine this has been a very difficult ordeal for us as a family, and particularly for him," Newman's son Jeff Newman said in a statement read outside his home in Pasadena Friday night, adding that they will say more about this unusual journey after Newman has rested.
Newman's release comes as U.S. Vice President Joe Biden visit to the region brought him to Seoul. Biden said Saturday that he welcomed the release and said he talked by phone with Newman in Beijing.
Associated Press writers Eun-Young Jeong, Hyung-jin Kim, Foster Klug and Josh Lederman in Seoul, Martha Mendoza and Paul Elias in San Francisco, and Didi Tang and Aritz Parra in Beijing contributed to this report.