North Korea appears likely to hold a military parade on Thursday to celebrate the country's 73rd founding anniversary, South Korea's Yonhap News Agency reported Tuesday.

Citing military sources, Yonhap said around 10,000 troops were earlier observed in Pyongyang, possibly indicating preparations for a military parade that would be the first of its kind to mark the state founding anniversary in almost three years.

A military parade is held in Pyongyang on Jan. 14, 2021. (KCNA/Kyodo)

It said fighters were recently observed flying over the capital city at night, while preparations appear to be under way at Mirim, a suburban airfield with a facility where parade rehearsals are known to take place.

South Korean officials are focused on whether any new weapons such as submarine-launched ballistic missiles will be made public at the military parade, if it takes place.

North Korea last held a military parade to mark the occasion in 2018, when it celebrated the state's 70th founding anniversary, though it held a military parade last year to mark the 75th anniversary of the founding of the ruling Workers' Party of Korea.

At the 2018 parade, which came around three months after the first-ever U.S.-North Korea summit, North Korea did not display intercontinental ballistic missiles that could target the United States, signaling leader Kim Jong Un's desire to refrain from provoking then U.S. President Donald Trump for the sake of moving forward with nuclear negotiations.

Trump met Kim two more times, but their talks made little progress, with the two countries at odds over issues such as the degree of sanctions relief Pyongyang should receive for denuclearization steps.

The holding of a Thursday parade by the armed forces could stem partly from last month's South Korea-U.S. joint military exercises that prompted the North to warn of a "serious security crisis."

Yonhap quoted a South Korean official as saying the event could be held at night just as with previous parades. The official added that the North could use the occasion to convey messages to South Korea and to the new U.S. administration of President Joe Biden.

On Oct. 10 last year, the North staged a predawn military parade in Pyongyang to show off a cutting-edge ICBM on the party's anniversary, in a rare move amid the coronavirus pandemic. It also unveiled an SLBM then.