Kim Jong Un was last seen presiding over a meeting on April 11.

Since missing a celebration commemorating his grandfather on the 15th before reports surfaced that he underwent cardiovascular surgery, questions about his health and whereabouts have circulated.

While there have been unconfirmed reports of his poor health and even death, South Korea media reported that a recent note written by Kim proves he's alive.

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It remains unclear if Kim Jong Un is alive or dead, but North Korea state media is using a thank-you note supposedly written by their supreme leader to prove the former, according to a South Korean press agency.

North Korean state media reported Monday that the note was recently sent to the builders of a tourist zone near where Kim's personal train was reportedly seen in recent days, according to the South Korea-based Yonhap News Agency.

"Supreme Leader Kim Jong-un has sent his appreciation to the workers who devoted themselves to building the Wonsan-Kalma tourist zone," the Rodong Sinmun, the North's main newspaper, said, echoing reporting from the Korean Central Broadcasting Station.

Questions about Kim's health, or whether he's even alive, have been circulating since CNN first reported on April 21 that he was in "grave danger" after cardiovascular surgery.

It was also noted that Kim, who is thought to be around 36, didn't appear at a celebration commemorating the 108th birthday of his grandfather, Kim Il-Sung, a week earlier.

North Korean state media have recently put out reports of Kim sending diplomatic letters and gifts, but there have been no reports on the leader's "field guidance" trips or photos of his public activities for more than two weeks, according to Yonhap News.

South Korean officials, however, have since said that Kim is well and believed to be staying in the Wonsan region of the country.

A North Korean monitoring project, 38 North, has also said a recent report that Kim's personal train was parked at a "leadership station" in Wonsan on April 21 and April 23.

The station is reserved for the use of the Kim family, the report said.

"The train's presence does not prove the whereabouts of the North Korean leader or indicate anything about his health, but it does lend weight to reports that Kim is staying at an elite area on the country's eastern coast," North Korean state media reported, according to Yonhap News.

The Wonsan-Kalma tourist zone is one of Kim's key pet construction projects, the South Korean news agency reported.

Kim, who sent a similar thank-you message to the workers in February, has sought to develop the North's tourism in an effort to beef up an economy faltering under international sanctions.

Wonsan occupies a special role in North Korean politics, acting as both a luxury getaway for elites and a testing ground for missile, artillery, and other military tests.