Image copyright KCNA Image caption The mass games are an enormous propaganda spectacle

North Korean leader Kim Jong-un has openly criticised one of his country's most important propaganda spectacles, the Mass Games.

According to state media, Mr Kim "seriously criticised" the games for "their wrong spirit of creation and irresponsible work attitude".

He had already called earlier this year for a new approach to propaganda.

North Korea is seen as preparing for more economic and ideological isolation, after US talks stalled.

What does Kim's criticism mean?

North Korea's mass games are a huge propaganda event featuring tens of thousands of participants, many of them children, in precision synchronised moves.

This year's games kicked off on Monday with what is supposed to be the beginning of a months-long propaganda festival, featuring enormous co-ordinated displays.

The games are designed to celebrate the country and boost morale, but Mr Kim's criticism is not unusual, analyst Minyoung Lee of NK Pro told the BBC.

"Kim Jong-un publicly criticises departments and poor work performance," she said, adding that his criticisms can range from public spectacles like the mass games to even mundane things like poor tree-planting.

Image copyright KCNA Image caption Kim Jong-un wants the country's propaganda to step up its game

Key to interpreting his criticism is the context of the past months. In March, Mr Kim said the country needed to do its propaganda in a "novel" way.

Since then, state media has increased its coverage of propaganda work and warned against "bourgeoisie ways of life" and "non-socialist phenomena," Ms Lee said.

Pyongyang under pressure?

The sudden pressure on propaganda may seem like a surprise, but Pyongyang's efforts make sense when seen against the recent failure of US-North Korea talks.

When negotiations with the South and Washington began, the propaganda machinery scaled down its criticism of those two traditional enemies.

"Pyongyang may feel insecure about the ramifications of the diplomatic detente and softer anti-South Korea and anti-US rhetoric on the people's mindset," explains Ms Lee.

Media playback is unsupported on your device Media caption 'I marched in a North Korea parade'

Yet the current diplomatic stalemate means it's unclear if talks with the US will continue.

Sanctions relief seems out of reach for now and the North will have to prepare its population for what could be prolonged economic difficulties.

This means "hardening the people's minds against outside influences and promoting domestic unity," said Ms Lee.

Kim's sister returns

Also in attendance at the opening of the games was Mr Kim's sister, who had not been seen publicly in nearly two months.

Kim Yo-jong has over the past two years become a close aide to her brother and was part of his diplomatic mission during the two US-North Korea summits in Singapore and Hanoi.

Image copyright KCNA Image caption Kim Yo-jong (left) seated not far from her brother

She has been absent from the public eye before, but her recent absence was by some observers linked to the failure of the negotiations with the US.

There were reports last week that several of North Korea's top officials had been purged or possibly even executed after the Hanoi summit.

With none of the reports verifiable, analysts have to read official photos and seating patterns for clues as to who might have fallen out of favour.

Kim Yo-jong appears to no longer be member of the Politburo, as some official photos show her too far from Kim Jong-un to still be part of that powerful body, Ms Lee said.

The fact that she sat only two chairs from her brother during the mass games is hard to interpret, as there is more flexibility in seating arrangements during performances like this one, Ms Lee added.

South Korean media last week speculated about two other diplomats having been purged. One of the them has since reappeared in photos alongside Mr Kim while the other's fate remains unclear.