The parade marked the once-every-five-years congress of the ruling Workers' Party, at which leader Kim Jong Un decried the US as his country's "foremost principal enemy".

"The world's most powerful weapon, submarine-launch ballistic missile, entered the square one after another, powerfully demonstrating the might of the revolutionary armed forces," the official KCNA news agency said.

The display included rockets with a "powerful striking capability for thoroughly annihilating enemies in a preemptive way outside the territory", it said.

Analysts say the North is using the congress to send Washington's incoming administration a message of strength in an attempt to extract concessions.

Kim and Donald Trump had a tumultuous relationship, engaging in mutual insults and threats of war before an extraordinary diplomatic bromance featuring headline-grabbing summits and declarations of love by the outgoing US president.

But little substantive progress was made, with the process deadlocked after their February 2019 meeting in Hanoi broke down over sanctions relief and what Pyongyang would be willing to give up in return.

The change of US leadership presents a challenge for North Korea: Biden is associated with the Obama administration's "strategic patience" approach and characterised Kim as a "thug" during the presidential debates.

"The majestic elite units and invincible iron-clad ranks of the Republic which will proudly pass Kim Il Sung Square represent our absolute power," North Korean defence minister Kim Jong Gwan said in a speech ahead of the parade, KCNA reported.