North Korea paraded its intercontinental ballistic missiles on Saturday in a massive military display in central Pyongyang, amid rising tensions across the region.
As tensions between North Korea and the US rose in recent days, speculation had grown that Kim Jong Un would conduct a nuclear test or other major military test.
Kim did not address the rally, which celebrates the 1912 birthday of his grandfather, Kim Il Sung - North Korea's founding ruler - and which is meant to send an unmistakable message to Washington about the isolated, nuclear-armed North's military might.
A US navy attack on a Syrian airfield this month with Tomahawk missiles raised questions about US President Donald Trump's plans for reclusive North Korea, which has conducted several missile and nuclear tests in defiance of United Nations sanctions, regularly threatening to destroy the US.
North Korea has said it had developed and would launch a missile that could strike mainland United States, but experts doubt this.
North Korea responded by warning of a "merciless retaliatory strike" if the USA acts first. Pictures on state television showed thousands of soldiers marching in formation alongside tanks, balloons and enormous crowds.
"Military analysts paid close attention to two new types of intercontinental ballistic missiles enclosed in canister launchers mounted on the backs of trucks - none of which had been displayed before".
North Korea did, however, hold a large military parade on the annual Day of the Sun celebration, in what The Washington Post described as "a defiant show of force in front of the world".
"We call on all parties to refrain from provoking and threatening each other, whether in words or actions, and not to let the situation get to an irreversible and unmanageable stage", Wang said, according to official news agency Xinhua.
One of the debuts included the Pukkuksong-2 SLBM, a submarine-launched ballistic missile, loaded on trucks, according to Reuters.
The source said: 'News of cadres of the second army corps slandering Kim Jong-un reached all the way to the People's Army's General Political Bureau, and the arrested cadres are to be severely punished'. President Donald Trump has issued repeated warnings about North Korea's nuclear ambitions, tweeting that the country is "looking for trouble" on Tuesday.
North Korea has been working on solid fuel - which, unlike liquid fuel, can be preloaded into missiles - as a way to fire missiles quickly to avoid prior detection by satellites.
Kim, the analyst, said it's likely that North Korea is also developing solid-fuel ICBMs, and that some of the rockets inside the canisters on Saturday might have been prototypes. The country conducted two nuclear tests past year.
Last year North Korea, which regularly fires off short-range rockets, launched a long-range missile and carried out two nuclear tests. South Korea has a spotty record of tracking developments in North Korea, as information about the secretive, authoritarian state is often impossible to confirm.