North Korea has 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.
Soldiers, tanks and other military hardware were paraded in Pyongyang in a show of strength on Saturday.
"We’re prepared to respond to an all-out war with an all-out war," North Korean military official Choe Ryong-Hae said, adding: "We are ready to hit back with nuclear attacks of our own style against any nuclear attacks."
North Korea staged an extravagant display of military strength at Saturday’s parade amid concern that mounting tensions in the region could lead to a conflict with the US.
Rows of military bands and columns of troops marched into Pyongyang’s main Kim Il-sung square in the heart of the city.
On display for the first time were what appeared to be submarine-launched ballistic missiles (SLBMs), which could be developed to house nuclear warheads capable of reaching targets around the world.
With concerns that the state is getting closer to successfully producing a nuclear arsenal, Saturday’s parade was an opportunity for Mr Kim to broadcast North Korea’s current military capabilities.
The event made clear how vital the state’s nuclear programme is to its future ambitions as it continues to ignore growing pressure from the US to abandon its nuclear weapons programme.
Tensions are high after the US military recently ordered a navy strike group to move towards the Korean peninsula.
North Korea has conducted five nuclear tests and a series of missile launches. Experts and government officials believe it is working to develop nuclear-warhead missiles that can reach the US.
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.
China, North Korea’s only backer, fears conflict could cause the regime to collapse and problems on its border.
"We call on all parties to refrain from provoking and threatening each other, whether in words or actions, and not let the situation get to an irreversible and unmanageable stage," Mr Wang said.
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! U.S.A."