An 85-year-old Korean War veteran and experienced globetrotter from Palo Alto is being detained in North Korea, where he was removed from a plane three weeks ago while leaving the reclusive country at the end of a visit — setting off a mysterious and tense diplomatic effort to free him.

North Korean authorities detained Merrill E. Newman on Oct. 26 as he and a neighbor wrapped up a vacation booked through a Beijing-based tour business.

The day before he was to depart, Newman met with North Korean officials, who discussed his Army service in the Korean War more than a half-century earlier, Newman’s son, Jeffrey Newman said Wednesday night.

Merrill Newman was slightly unnerved, his son said, but went to dinner and thought nothing of it until the next day, five minutes before take-off, when he was escorted off the plane.

His traveling companion, Bob Hamrdla, released a statement Wednesday afternoon, calling Newman’s detention “a terrible misunderstanding.”

“I hope that the North Koreans see this as a humanitarian matter and allow him to return to his family as soon as possible,” said Hamrdla, a former assistant to the president of Stanford and secretary to the board of trustees.

Jeffrey Newman said it’s hard to believe his father’s military service would be the reason for his detention. “There have been other Korean veterans who’ve been back,” he said. “My dad was not breaking any new ground.

“He’s always wanted to go to North Korea; it’s been a lifelong thing,” the younger Newman said. “Like the guys who go back to Normandy, the World War II veterans. These places had profound, powerful impacts on them as young men, and he wanted to see it again.”

Since the United States has no diplomatic relations with North Korea, Newman’s family has been working through State Department officials and the Swedish Embassy to secure his release.

Jeffrey Newman said the Swedish ambassador delivered his father’s heart medication to the North Korean foreign affairs ministry, “but we don’t know what happened to it after that.”

His mother, he said, “is amazingly strong, but this is incredibly difficult.”

“There’s some misunderstanding here, a terrible misunderstanding, and my father has always had a deep respect for the Korean culture and the Korean people,” he said. “We need to see what we can do to resolve that misunderstanding and return him home to his wife and grandchildren and put this behind us.”

North Korea hasn’t formally acknowledged it is holding Newman, much less a reason why — which an expert on that nation called particularly odd. And the State Department on Tuesday heightened a travel warning for North Korea but would neither link the advisory to Newman’s detainment or even confirm he is the American being held.

Residents at the Channing House retirement complex, where Newman lives with his wife in downtown Palo Alto, said his detention has been the topic of conversation for weeks.

“We’re all distressed, and we feel very strongly in support of” Newman’s wife, said Bill Blankenburg, 81. When asked why he thought Newman might have been taken, he said, “I don’t think anyone has an idea of what’s going on in the minds of the North Koreans.”

A brief biography in the complex’s newsletter says the Newmans have traveled the world after retiring, including sailing trips from Panama to Ecuador and from Colombia to Guatemala.

Another Channing House newsletter described how Merrill Newman took Korean language lessons to prepare for his 10-day trip with Hamrdla, who directed three of Stanford’s Overseas Study Centers in Europe and has led more than 40 travel-study programs in Central Europe. The newsletter said the two would be accompanied by two Korean guides.

In May, Newman praised on Amazon.com the Bradt travel guide to North Korea as “a must have if you are considering a trip to North Korea.”

Another Channing House resident, who did not want to give her name, said she spoke with Newman before he left on his trip.

“I said, ‘Why do you want to go to a place that’s dangerous? I wouldn’t want to go,'” she said. “His reaction was very relaxed, with a smile. He went just as a fun trip. He wasn’t there for any particular reason. They were travelling.”

Newman retired in 1984 after a career as a finance executive for tech companies, including Convergent Technologies and Shugart Associates.

He earned a bachelor’s degree in zoology from UC Berkeley in 1950 before joining the military and serving as an infantry officer during the Korean War. After the war, he earned a master’s degree in education from Stanford while teaching math, science and swimming at high schools in Berkeley and Livermore.

The Palo Alto chapter of the American Red Cross recognized him in 2008 for 50 years of volunteer service; he served on the chapter’s board for decades and also taught CPR and first aid through the organization.

Daniel Sneider, a North Korea expert, said it’s not unprecedented for North Koreans to arrest American travelers.

“But even by North Korean standards, this is unusual,” said Sneider, associate director for research at Stanford’s Walter H. Shorenstein Asia-Pacific Research Center.

Most previous detentions of U.S. citizens involved Korean Americans, Sneider said. But he can’t recall any case in which a tourist like Newman, with no apparent Korean ties, was detained.

“It’s also very unusual for the North Koreans not to acknowledge, particularly after holding the person for weeks, that they have the person,” he said. “That may indicate that they haven’t decided what to do with him yet, and therefore they don’t want to admit that they’ve arrested him.”

North Korea was much more open about the arrest last year of Kenneth Bae, a Korean-American Christian missionary and U.S. citizen who now is the longest-serving U.S. detainee in North Korea since the end of the Korean War. Accused of planning a religious coup, he was sentenced in April to 15 years of hard labor.

But the reason for Newman’s detention remains puzzling. Newman’s son said there’s no indication his father has been confused with a decorated Marine Corps 2nd lieutenant with a strikingly similar name Awarded the Silver Star in 1952 for heroically leading his men against North Korean troops. Merrill H. Newman of Fairview, Ore. — now 84 and living in Beaverton, Ore.– said “it is kind of creepy” that a Korean War veteran of so similar a name is now imprisoned in North Korea.

“It’s a darn shame for that guy. I hope they get him out soon,” he said, adding he hasn’t traveled to North Korea since the war. “I’ve been there, done that, and I don’t want to go back.”

Josh Richman covers politics. Contact him at 510-208-6428. Follow him at Twitter.com/josh_richman.