Kim Jong Un
Kim Jong UnReuters

The US is monitoring intelligence that North Korea's leader, Kim Jong Un, is in grave danger after undergoing surgery, a US official with direct knowledge told CNN on Monday.

Kim recently missed the celebration of his grandfather's birthday on April 15, which raised speculation about his well-being. He had been seen four days before that at a government meeting.

The National Security Council and Office of the Director of National Intelligence declined to comment when reached by CNN.

The network has also reached out to the CIA and the State Department for comment and sought comment from the South Koreans.

North Korea tightly controls any information surrounding its leader. His absences from official state media often spark speculation and rumors about his health.

CNN noted that Kim last appeared in North Korean state media on April 11. April 15 -- North Korea's most important holiday, the anniversary of the birth of the country's founding father, Kim Il Sung -- came and went without any official mention of Kim Jong Un's movements.

Experts are unsure of what to make of Kim's absence from any festivities celebrating his grandfather. When North Korean leaders have not shown up to these important celebrations in the past, it has portended major developments, but it has also turned out to be nothing.

The network noted that Kim Jong Il's absence from a parade celebrating North Korea's 60th anniversary in 2008 was followed by rumblings that he was in poor health. It was later revealed he had a stroke, after which his health continued to decline until his death in 2011.

Kim Jong Un disappeared from the public eye for more than a month in 2014, which also prompted speculation about his health. He returned sporting a cane, and days later South Korean intelligence said that he had a cyst removed from his ankle.

The report comes amid a prolonged hiatus in disarmament talks with the United States.

Kim and US President Donald Trump engaged in months of mutual insults and threats of devastation in 2017, sending tensions soaring before a diplomatic rapprochement the following year.

The pair have met three times since June 2018, most recently in Vietnam in February of 2019, but with little progress towards denuclearization.

Since those talks broke down, North Korea has conducted several tests of ballistic missiles.

Pyongyang set a unilateral end-2019 deadline for Washington to offer fresh concessions. In his New Year’s message after his ultimatum to the US expired, the North Korean leader said his country would continue developing nuclear programs unless the US gave up its hostile approach.