Today, the Kremlin announced that Kim Jong Un will not be attending next week’s events in Moscow commemorating the 70th anniversary of the end of World War II. “He has decided to stay in Pyongyang,” said spokesman Dmitry Peskov. “This decision is related to North Korea’s internal affairs.”

The announcement was generally unexpected. Among those taken by surprise was South Korea’s National Intelligence Service, which had just issued a report to the National Assembly’s Intelligence Committee on the topic. Yesterday, two lawmakers, including one from the ruling Saenuri Party, revealed the NIS believed that the North Korean leader was still planning on attending the victory celebration in the Russian capital.

The cancellation is all the more startling because Kim had been expected to meet Russian President Vladimir Putin during his trip. Since the end of 2013, when he had his wife’s uncle Jang Song Thaek put to death, Kim has been busy cutting ties to long-time sponsor China and racing to build relations with the Kremlin. Jang had served as Pyongyang’s point man for relations with Beijing.

There are other hints that all is not right in Pyongyang. The NIS assessments released yesterday also noted that Kim had ordered the execution of 15 senior officials this year.

The South Korean intelligence serviced reported that a vice minister was killed in January for questioning Kim’s forestry policy. In February, a State Planning Commission official was put to death over the leader’s plans to construct a science and technology hall in the shape of the flower named after Kim Il Sung, his grandfather and founder of the North Korean state. And last month, four senior members of Pyongyang’s Unhasu Orchestra, including its general director, faced a firing squad for either espionage or a crime of lesser import.

This report comes on the heels of news that sometime from November to February, Kim handed a death sentence to an army four-star general, Pyon In Son, reportedly for refusing orders to fire junior officers who had contact with China.

The most publicized execution is that of Jang, believed to be the second-most powerful figure in the regime at the time. Jang was killed in December 2013, probably by anti-aircraft fire.

In total, the NIS believes that Kim had ordered 17 senior officials killed in 2012, 10 the following year, and 41 in 2014.

The continuing executions are indications that Kim perceives his position inside the regime to be shaky. And his decision not to leave the country—Russia would have been his first foreign trip since becoming leader—seems to confirm that assessment. Rulers, especially of one-man systems, are particularly vulnerable when not at home.

Most analysts had determined that Kim had quickly consolidated power after the December 2011 death of his father, Kim Jong Il. Those assessments are almost certainly wrong, however.

For one thing, the young Jong Un came to power unexpectedly soon and so did not have sufficient time to build a base inside the regime from which to rule. Since then, his constant shuffling of top military officers is a sure signal he has not found generals he can trust.

And although he has executed many, the deaths have nonetheless continued. “The most easily discernable sign of weakness in the power structure, or an inability to fully control a government, is purges—and in North Korea there have been plenty of them,” writes Bruce Bechtol in his latest book, North Korea and Regional Security in the Kim Jong-un Era: A New International Security Dilemma.

If the country were indeed stable, there would have been no need for the bloodletting, both figurative and literal.

Most analysts believe Kim Jong Il had consolidated his position by 1997, three years after the death of his father, Kim Il Sung. Kim Jong Un, however, has already passed the three-year mark. Bechtol reports that Kim Jong Un has ordered far more executions than his father had during the corresponding periods of their rule.

Why have there been so many killings? For one thing, Kim Jong Un needed to create room to install officials loyal to him. And he, of course, felt the need to remove potential competitors.

Moreover, the nature of the regime is changing in subtle but important ways. Kim Il Sung created a one-man system where no one constituent element dominated. The Korean Workers’ Party, the Korean People’s Army, and the security services all kept one another in check—surveilling, reporting on, and challenging each other. The Great Leader, as he liked to call himself, perfected the art of keeping everything in balance.

Kim Jong Il, the second-generation of the dynasty, was far weaker than his dad. As a result, he needed to create a power base to call his own. He did that the fast wa:y by letting the military gain prominence, pushing the two other groupings to the sidelines. That, in a nutshell, is songun, his military-first policy.

Under the guidance of Jang Song Thaek, young Kim Jong Un restored balance, bringing back the Party from the fringes of power. With Jang’s death, however, the military has been making a comeback of its own. Kim Jong Un has resisted the trend to some degree with his constant churning and even execution of senior officers.

Yet Kim has also had to appease the military by acceding to its wish to accelerate missile and nuclear weapons programs. Yesterday, the Institute for Science and International Security reported (PDF), among other findings, that the North has resumed operations at its only plutonium reactor, in Yongbyon. Earlier this month, Stanford University’s Siegfried Hecker revealed that a Chinese government think tank had estimated Kim has a bigger arsenal of plutonium and uranium warheads than others thought and NORAD chief Admiral William Gortney publicly said North Korea could hit the West Coast of the U.S. with its newly deployed, road-mobile, and nuclear-capable KN-08 missile.

In a period of regime instability, the path of least resistance for Kim Jong Un is to arm fast and challenge the U.S. and other perceived enemies of the North Korean state. Good politics in Pyongyang mean trouble everywhere else.

Gordon G. Chang is the author of Nuclear Showdown: North Korea Takes On the World. Follow him on Twitter @GordonGChang.