International media was not invited to cover the parade, which was to feature "hundreds" of rockets and missiles, diplomatic sources said last month.
South Korean news agency Yonhap reported that as many as 50,000 people gathered in Kim Il Sung square to watch the event, which included around 13,000 soldiers.
The parade began at 10:00 a.m. Pyongyang time, a diplomatic source with deep knowledge of North Korea's activities told CNN. It's possible that North Korean state television will air video of the event during its afternoon broadcast.
The parade was held around the same time as a welcoming ceremony for hundreds of North Koreans who are in South Korea for the 2018 Winter Olympics.
For North Korean leader Kim Jong Un, the parade is an opportunity to stoke patriotic fervor and to remind the world of his country's rapid progress on its nuclear program.
For South Korea, it's a poke in the eye after efforts by President Moon Jae-in to present a united front as the two Koreas compete under the same flag.
"The North Koreans tend to act out like this even during periods of quiet to demonstrate their independence and to try to convince us that their nuclear arsenal is beyond limits," said Adam Mount, a senior fellow at the Federation of American Scientists.
"It's a clear sign of defiance, and they intend it to be."
Pyongyang's parades offer an unparalleled opportunity for intelligence analysts to get images of military equipment from one of the world's most reclusive places.
, many in the open-source intelligence community that track North Korea's weapons program were surprised by the sophisticated missiles on display.
Nonproliferation experts said during Thursday's parade it's possible Pyongyang could show some mock-ups of their newer technology, like a new long-range, solid-fueled ballistic missile.
A diplomatic source told CNN the event was expected to include
of "hundreds" of missiles and rockets in an attempt "to scare the hell out of the Americans."
Based on combination of factors, including satellite imagery analysis and insights from diplomatic sources, analysts say it's possible North Korea will attempt to show the world that it is in the process of mass-producing the technology it showed off last year, like the Hwasong-15 intercontinental ballistic missile (ICBM).
"If we were to look at last year, we saw lots of new technology. I think this year it will definitely be an opportunity for North Korea to show off the things it tested last year," said Melissa Hanham, a senior research associate at the Middlebury Institute for International Studies' Center for Nonproliferation Studies.
However, last year's parade was open to members of the international media, including CNN. This year Pyongyang has only invited a handful of diplomats and will control all the imagery that goes out. And North Korea has a history of doctoring pictures it releases to the world.
It's also unclear when photographs and video would actually go public. Though North Korean state television does cover some events live, Pyongyang sometimes does not confirm news of their military accomplishments -- like missile tests -- until a full 24 hours after the rest of the world knows. The fact that YouTube has shut down some North Korea propaganda channels
may make it even harder to get pictures of the parade.
"It's going to be tougher to get images out that aren't carefully scripted by North Korea. There's probably a wide variety of reasons why that may be happening," Hanham said. "Maybe they're trying to prevent something small ... or maybe they realize that they are giving away a lot of intelligence."
A new date
North Korea has been holding military parades since the early days of Kim Il Sung's reign. The grainy images of soldiers marching in front bear undeniable similarities to those that come from North Korea today.
These displays of military might aren't a specific North Korean phenomenon. They date back to Roman times, when the city would celebrate victories of generals and their armies.
As in ancient times, the parades are used to stoke patriotic fervor. They're essentially pep rallies with weapons -- the weapons have just gotten deadlier over the years. And plenty of countries still hold them.
China held its own massive military display last year
. So did Russia
The parades aren't limited to more autocratic states. France holds a parade on Bastille day, which US President Donald Trump attended last year. That display has reportedly prompted the President to ask the Pentagon to plan an American military parade
, something which has not been seen in years (though some argue the inaugural parade every four years has a martial feel to it.)
But Thursday will be the first time North Korea has held a parade on February 8 in some time.
From the 1970s until 2014, North Korea has celebrated its Army Day on April 25, the day the Korean People's Revolutionary Army -- the guerrilla forces fighting Japanese occupation -- was founded in 1932.
North Korean history claims
that Kim Il Sung -- the country's founder and grandfather of the current leader -- transformed the KPRA into the country's armed forces on February 8, 1948, after the Korean Peninsula was divided into two countries.
Analysts suspect Kim Jong Un revived the February celebration in 2015 in an attempt to "put his own stamp on things."
The country's most important holiday, however, is the Day of the Sun, the anniversary of Kim Il Sung's birth on April 15. That's when last year's massive military parade was held.