China will showcase its military prowess with troops marching in formation, flypasts and displays of high-tech fighting gear at the showpiece extravaganza centred on Beijing's Tiananmen Square to mark 80 years since the end of World War II.

Millions of Chinese people were killed during a prolonged war with imperial Japan in the 1930s and 40s, which became part of a global conflict following Tokyo's attack on Pearl Harbor in 1941.

All eyes will be on how the trio of Xi, Putin and Kim -- who rarely leaves secretive North Korea -- interact with each other in a highly choreographed photo opportunity seen as a coup for China on the world stage.

Wednesday's 70-minute event is the climax of a whirlwind week for President Xi, who on Sunday and Monday hosted a slew of Eurasian leaders for a summit in the northern port city of Tianjin aimed at putting China front and centre of regional relations.

The club of 10 countries, named the Shanghai Cooperation Organisation (SCO), touts itself as a non-Western style of collaboration in the region and seeks to be an alternative to traditional alliances.

During the summit, Xi slammed "bullying behaviour" from certain countries -- a veiled reference to the United States -- while Putin defended Russia's Ukraine offensive, blaming the West for triggering the conflict.

Many of the guests from the Tianjin gathering, including Putin, Belarusian President Alexander Lukashenko and several other leaders will join Xi for the parade in Beijing.

However, no major Western leaders will attend the event.

- Hardware on show -

Security around Beijing has tightened in recent days and weeks, with road closures, military personnel stationed on bridges and street corners, and miles upon miles of white barriers lining the capital's wide boulevards.

Art installations with flowers, doves and an emblem showing the Great Wall of China with "1945-2025" have cropped up around the city, and Chinese flags are flying in residential neighbourhoods.

Officials have been tight-lipped over the list of hardware to be displayed at the parade, but military enthusiasts have already spotted significant new systems, including what is rumoured to be a gigantic laser weapon.

Defence experts have been analysing social media photos and footage from recent rehearsals, which have shown anti-ship missiles, cutting-edge underwater drones and anti-missile systems.

The military has said all the equipment presented is domestically produced and "in active duty".

- Kim rolls in -

China has touted the parade as a show of unity with other countries, and Kim's attendance will be the first time he is seen with Xi and Putin at the same event. It is only his second reported trip abroad in six years.

AFP journalists captured the moment his olive-green train approached Beijing Railway Station on Tuesday afternoon, with small North Korean flags flying over one coach.

Photos released by the official Korean Central News Agency (KCNA) showed Kim smoking a cigarette outside a carriage with Foreign Minister Choe Son Hui and close aide Jo Yong Won.

Another pictured Kim grinning inside his lavish, wood-lined train carriage in front of a national flag and emblem.

Kim enjoyed a brief bout of high-profile international diplomacy from around 2018, meeting US President Donald Trump and then South Korean president Moon Jae-in multiple times.

But he withdrew from the global scene after the collapse of a summit with Trump in Hanoi, Vietnam, in 2019.

Kim stayed in North Korea throughout the Covid-19 pandemic, but met Putin in Russia's far east in 2023.