(CNN) -- The U.S. government is "deeply concerned" about two American citizens detained in North Korea, including recently detained 85-year-old Merrill Newman, a National Security Council spokeswoman said.
"Given Mr. Newman's advanced age and health conditions, we urge (North Korea) to release Mr. Newman so he may return home and reunite with his family," said Caitlin Hayden, the NSC spokeswoman.
Newman suffers from a heart condition, according to his son, Jeff Newman. Swedish diplomats -- acting on behalf of the United States, which does not have formal ties with North Korea -- tried to deliver Newman medication to treat his ailment, but his son has said he is not sure it got to him.
North Korea's state-run KCNA news service reported early Saturday that Newman had apologized for crimes he had committed against North Korea, both while serving in the U.S. military during the Korean War and during his trip back to North Korea earlier this fall.
Another American being held in North Korea, Kenneth Bae, was arrested in November 2012 and sentenced in May to 15 years of hard labor.
The North Korean government has said he was found guilty of "hostile acts" and attempts to topple the government.
Weeks after detention, finally an explanation
According to his family, Newman had gone on a 10-day organized private tour of North Korea in October. From phone calls and postcards he sent, the trip was going well and there was no indication of any kind of problem, Jeff Newman said.
The day before he was to leave, "one or two Korean authorities" met with Newman and his tour guide, the son added. They talked about Newman's service record, which left "my dad ... a bit bothered," according to Jeff Newman.
Then, just minutes before his Beijing-bound plane was set to depart Pyongyang, the retired financial consultant and Korean War veteran was taken off the aircraft by North Korean authorities.
Until Saturday, the North Korean government hadn't said why it held Newman, who is from Palo Alto, California. CNN reached out to the veteran's family, but received no immediate response.
The explanation came in the form of a published apology from Newman, as well as accompanying images of him thumbprinting his handwritten note and talking about his experiences.
Atop the first of the four handwritten pages is the word "apology," according to video released by North Korea. The end of the last page is dated November 9 -- indicating Newman made his reported admission 20 days ago.
Why might Pyongyang have waited 21 days, then, to make the admission public? That's another one of the mysteries surrounding this case.
State news: 'Investigation clearly proved ... hostile acts'
In the note, Newman talked about his having advised the Kuwol Unit, part of the "intelligence bureau" fighting against Pyongyang in the Korean War. He detailed how he commanded troops to collect "information" and wage various deadly attacks.
"After I killed so many civilians and (North Korean) soldiers and destroyed strategic objects in the DPRK during the Korean War, I committed indelible offensive acts against the DPRK government and Korean people," Newman said, according to the "apology" reported by KCNA.
The reported message also touches on his return 60 years later to North Korea, admitting that he "shamelessly ... had a plan to meet any surviving soldiers and pray for the souls of the dead soldiers."
"I have been guilty of big crimes against the DPRK government and the Korean people again," Newman adds in the "apology."
His statement ends: "If I go back to (the) USA, I will tell the true features of the DPRK and the life the Korean people are leading."
In addition to this statement, KCNA ran a story alleging Newman came to North Korea with a tourist group in October and afterward "perpetrated acts of infringing upon the dignity and sovereignty of the DPRK and slandering its socialist system."
This story claimed that Newman tried to "look for spies and terrorists who conducted espionage and subversive activities against the DPRK."
Investigators determined that, as a member of the U.S. military, he "masterminded espionage and subversive activities ... and, in this course, he was involved in the killings of service personnel of the Korean People's Army and innocent civilians."
"The investigation clearly proved Newman's hostile acts against the DPRK, and they were backed by evidence," the KCNA story added. "He admitted all his crimes."
Other detained Americans
Status in limbo after 'apology'
Just five days ago -- albeit more than two weeks after Newman may have made his apology -- his wife Lee said she hoped he would be home for Thanksgiving.
"We need to have Merrill back at the head of the table for the holidays," Lee Newman told CNN's Wolf Blitzer. "And we ask -- respectfully -- for them to release him and let him come home."
One day before Thanksgiving, Rep. Charlie Rangel -- a fellow Korean War veteran -- released a letter urging North Korean leader Kim Jong Un "to release him immediately." Pointing to Newman's medical issues, the New York Democrat implored Kim to "have the heart to reunite him with his loved ones and those who can provide proper care."
Rangel also reflected on the 1950s war, as well as the current state of affairs between the key players.
"I believe that Mr. Newman, like myself and others who have fought during the Korean War six decades ago, wants to see a united Korea in our lifetime," wrote the congressman. "While progress has been slow on the political front, I am confident it can be advanced on humanitarian grounds."
So will there be fresh movement in Newman's case? Will his reported apology pave the way for his release or will it be followed, like Bae, with a lengthy prison sentence?
As of Saturday, nobody -- at least nobody outside of North Korea -- seems to know.
CNN's Chelsea J. Carter and Ashley Killough contributed to this report