He is expected to use the trip to hold face-to-face meetings with both the Chinese and Russian presidents.

AFP breaks down why this visit is so significant:

- A rare outing -

Since he came to power in 2011, Kim has only made a handful of known trips outside North Korea's borders.

China is the country he has visited most -- four times previously -- and he has travelled to Russia twice.

His most adventurous travel came seven years ago, when he met US President Donald Trump in Singapore in June 2018, followed by another summit in Hanoi in early 2019.

Kim has also travelled twice to the Joint Security Area at the border of North and South Korea.

- 'Unusual risk' -

These past trips have been tightly controlled bilateral affairs, ensuring Kim remained the centre of attention.

On Wednesday he will find himself among a throng of international leaders.

"It is an unusual risk," the International Crisis Group (ICG)'s Christopher Green told AFP.

"Kim does not generally participate in multilateral events, because it is hard to control the political messaging... it will be interesting to see how the North Koreans manage it."

- Symbolic -

The presence of Kim, Xi and Russia's Vladimir Putin together at a parade bristling with missiles, tanks and fighter jets is powerfully symbolic -- a vision of an alternative to the post-war US-led world order.

"Japan is the main target of Beijing's propaganda on Wednesday, alongside the US-led Western bloc," said James Char from Singapore's Nanyang Technological University, adding Kim's presence gave the impression of "a united front".

It is also a messaging win for Kim domestically -- signalling to North Koreans that the internationally isolated regime is respected by two world powers, China and Russia.

- First foreign parade -

Kim is no stranger to grand military parades at home, but it is the first time he is attending someone else's.

North Korea did not exist as a state in 1945 -- it was founded in 1948 -- but Kim's grandfather Kim Il Sung fought against Japanese occupying forces in Manchuria.

The contribution of Koreans in general to the resistance against Japan continues to foster a shared military memory with China.

- Uneasy allies -

Despite the apparent closeness though, Beijing and Pyongyang's relationship is an uneasy one.

"China and North Korea are not friends, and nor are they true allies," said ICG's Green.

"China sees North Korea's existence as helpful" as a point of diplomatic leverage, as well as a buffer state and a source of cheap labour, he explained.

Its support of the Kim regime is predicated on the expectation it will not cause too much regional instability -- an expectation that has not always been lived up to.

Kim's "consistent policy has been to find other avenues for support and security so as to minimize the leverage that China has over North Korea, and maximise North Korea's freedom of action", said the University of Sydney's Justin Hastings.

Russia and North Korea last year signed a mutual defence agreement, and North Korean soldiers are fighting in the Ukraine war.

Kim's invitation to the parade confirms Xi's desire to keep North Korea in Beijing's orbit, even as Pyongyang deepens its ties with Moscow, said Hastings.