It was South Korea's biggest Armed Forces Day ceremony in a decade, and the first since North Korea conducted its third atomic test and threatened nuclear war earlier this year.
About 11,000 troops, 190 weapons systems and other equipment and 120 aircraft were featured in the ceremony at a military airport just south of Seoul. Among them were GPS-guided, Hyunmu-3 cruise missiles with a range of 1,000 kilometers (620 miles) that South Korea developed in recent years. It was the first time the domestically built Hyunmu-3 was publicly shown, according to Seoul's Defense Ministry.
President Park Geun-hye said in a speech at the ceremony that South Korea must maintain its strong alliance with the U.S. and establish missile defense and pre-emptive strike capabilities to let North Korea know "the nuclear weapons and missiles it is obsessed with are useless."
"We must build up a strong deterrence against North Korea until it puts down its nuclear weapons program and make a right choice for its own people and peace on the Korean Peninsula," she said as visiting U.S. Defense Secretary Chuck Hagel sat nearby.
The Korean Peninsula is still officially at state of war because the 1950-53 Korean War ended with an armistice, not a peace treaty. About 28,500 U.S. troops are deployed in South Korea.
Other new weapons on show for the first time Tuesday included the Hyunmu-2 ballistic missile with a range of 300 kilometers (185 miles) and Israeli-made Spike missiles aimed at neutralizing North Korean coastal artillery.
South Korea has deployed the Spike missiles at front-line islands after one of those islands were shelled by North Korea and four people were killed in 2010.
"It's a kind of show of force. North Korea shows off its missiles on national anniversaries. We can understand today's ceremony in the same vein," said Lee Daewoo, a security analyst at the private Sejong Institute near Seoul. "Today is Armed Forces Day, and (South Korea) is clearly showing that it has the capability to punish" North Korea.
He said he expects North Korea to respond angrily to the ceremony.
North Korea typically marks national anniversaries with lavish, choreographed military parades featuring goose-stepping soldiers and arrays of weapons designed to rally public support behind the country's leadership and stoke fear among enemy countries. It's one of the few chances that outsiders can look at North Korea's military and its weapons systems.
Later Tuesday, South Korean troops, columns of tanks and artillery and missiles carried on mobile launchers paraded through downtown Seoul, with white confetti being floated into the air and citizens lining the streets and waving small national flags. It was South Korea's first military parade through the streets of Seoul since 2008.
Large-scale Armed Forces Day celebrations are normally held every five years, when a new president takes office. In 2008, however, the event was smaller, with fewer soldiers mobilized for the parade and the ceremony held at a sports stadium, instead of a military airport.
Park took office in February for a single five-year term with a policy that combines vows of strong counter-action to any North Korea provocation with efforts to build trust and re-establish dialogue.
After its flurry of springtime threats, Pyongyang eased its rhetoric but still repeatedly vowed to bolster its nuclear arsenal to cope with what it calls U.S. military threats. North Korea then sought the resumption of stalled joint cooperation projects with South Korea before it recently abruptly cancelled the reunions of families separated by war.