North Korea on Saturday warned the US not to take provocative action in the region, saying it is "ready to hit back with nuclear attacks".
The comments came as North Korea marked the 105th anniversary of the birth of its founding President, Kim Il-sung, grandfather of leader Kim Jong-un.
A huge parade in Pyongyang was held amid speculation that current leader Kim Jong-un could order a new nuclear test, reported BBC.
Among the hardware on display appeared to be new intercontinental and submarine-launched ballistic missiles.
On display for the first time were what appeared to be the Pukkuksong submarine-launched ballistic missiles (SLBMs), which have a range of more than 1,000 km.
Weapons analysts said there also appeared to be two new types of intercontinental ballistic missiles in canister launchers, but it remains unclear whether they have been tested.
The show of strength comes amid mounting tension, with a US aircraft carrier group steaming towards the region.
"We're prepared to respond to an all-out war with an all-out war," said Choe Ryong-hae, believed to be the country's second most powerful official.
"We are ready to hit back with nuclear attacks of our own style against any nuclear attacks," he said.
Rows of military bands and goose-stepping and sword-wielding soldiers marched through Pyongyang's main Kim Il-sung square for the "Day of the Sun" celebrations, as a black-suited Kim Jong-un watched.
He was seen clapping and smiling from a reviewing box. Pictures on state television showed thousands of soldiers marching in formation alongside tanks, balloons and enormous crowds.
During the pomp and circumstance at Kim II Sung square, citizens showed their revolutionary fervour with choreographed performances while vehicles displaying North Korea's military arsenal rolled by.
On Friday, China's Foreign Minister Wang Yi warned that "conflict could break out at any moment", adding that if war occurred there could be no winner.
Unlike at previous Pyongyang parades there did not appear to be any Chinese representatives present, according to a BBC report.
Adding to Chinese unease, US President Donald Trump said on Thursday that "the problem of North Korea" would be "taken care of".
"If China decides to help, that would be great. If not, we will solve the problem without them! USA."
Vice-President Mike Pence will be in South Korea on Sunday as part of a 10-day Asia trip.
The aircraft carrier USS Carl Vinson and an accompanying battle group have also been sent to the Korean peninsula.
"We are sending an armada. Very powerful," Trump had told the Fox Business Network. "He is doing the wrong thing," he said of Kim Jong-un. "He's making a big mistake."