— -- This isn't the first time that Kim Jong-un has gone missing but the North Korean leader is breaking his own record by staying out of the public eye for this long.
Purposefully disappearing for long periods of time is a move long used by dictators, including former Venezuelan President Hugo Chavez and Cuban President Fidel Castro, and though Kim Jong-un's absence for more than a month has sparked the international rumor mill.
The 31-year-old dictator learned the power of the vanishing act from the best of them: his father. Kim Jong-il "went missing" for up to 80 days when he reportedly had a stroke in 2008. Potential health issues remains the most likely reason for Kim Jong-un's notable absence, and it is a reason he has not used before.
"No one knows why Kim Jong-un is out of sight, but he has been the most public of the three dynastic leaders," Katherine Moon, a senior fellow for the Center for East Asia Policy Studies, told ABC News, referring to the line of leadership that began with Kim Jong-un's grandfather, Kim Il-sung. She said that his increasing weight, alcoholism, heart or ankle problems and stress are all among the health factors that could be ailing him, though nothing has been confirmed.
"He may also be facing personal challenges -- he does have a family -- a wife and at least one child. Perhaps there is illness or some other problem. Again, who knows?" Moon said.
North Korea expert Michael Madden, who runs a leadership watch blog and contributes to Johns Hopkins University's Korean Studies site, told ABC News that there were two other times that he has gone missing since taking control of the country following his father's death in December 2011.
The first came in June 2012, when he went missing for about three weeks. As with many things in North Korea, the lack of transparency means that nothing is known for sure, but Madden said that this absence lined up with when the supreme leader's wife would have been entering the second trimester of her pregnancy, leading him to believe that it was his wife's health that kept him out of the spotlight rather than his own.
"There's no reason to really think it was his health back then," Madden said. "He was more muscular than he is now."
The second absence came in April 2013, though he was only out of the public eye for about two weeks immediately after a rather turbulent political period, so it may have been a strategic move on the part of his advisers.
"Given that the DPRK regime is the most opaque on earth, it's not surprising that there is very little reliable and publicly available information about this," National Security Council spokesman Patrick Ventrell told ABC News regarding Kim's latest disappearance, referring to North Korea by its official name, the Democratic People's Republic of Korea.
Former Venezuelan President Hugo Chavez remained out of sight for more than two months while he recovered from his fourth cancer-related surgery in December 2012, according to the Associated Press.
At the time, the state's foreign minister made regular public updates, at one point telling how Chavez was "in charge and making decisions." One noted difference between the Chavez absence at the time and Kim Jong-un's latest vanishing period is the relative openness that Venezuelan officials used to address the issue. Chavez was seen waving to supporters as he boarded the plane to Cuba for his surgery, and officials told the Associated Press that "it's a slow, slow recovery process."
When Kim Jong-il is believed to have had his stroke in 2008, North Korean press officials did their best to prevent any admission of ill health. Madden said that officials claimed Kim Jong-il attended two public events during his roughly 80-day absence, though there were no photos taken at one event and the images released from the second were believed to be doctored.
One factor that makes Kim Jong-un's ongoing absence different from the rest of the dictatorial pack is his age. Though his health is clearly a cause for concern -- since he has grown noticeably larger and was seen limping in his last public appearance -- his age makes the prospect of a grave medical issue less of a concern.
Each time Fidel Castro is not seen for long periods, which occurs regularly, a fresh crop of death rumors begins to circulate. One of the longest stretches came last year, when, at 87, he wasn't seen for eight months and, according to the Associated Press, that stretch was broken on Jan. 8 when he attended a gallery opening in Havana.
Kim Jong-un acknowledged his absence from Friday's celebration of the national party's anniversary by sending flowers that were placed in front of statues of his father and grandfather.
"I'm going to give Kim Jong-un until Monday to show up," Madden said.