Experts on North Korea speculate that the country will likely hold a large military parade on Wednesday as part of national celebrations to mark the 75th anniversary of the Korean People's Army.

Satellite photos released by a US research group in January showed what appeared to be preparations for a parade in a square in central Pyongyang.

The imagery raised speculation that a large parade will be held to foster unity within the country and show to the world that North Korea is stepping up its nuclear and missile development.

It will be the first parade since April last year, when the North marked 90 years since the foundation of the current military's predecessor, the Korean People's Revolutionary Army.

Attention is on whether the parade will feature new weapons or whether North Korean leader Kim Jong Un will give an address.

Kim has said the country needs to mass-produce tactical nuclear weapons, "exponentially" increase production of nuclear warheads and develop a new intercontinental ballistic missile in 2023, the third of its five-year defense plan.

On Monday, the Central Military Commission of the ruling Workers' Party decided to constantly strengthen the operation and combat drills of the military and more rigorously perfect its preparedness for war.