North Korea says "hostile" America is "inciting military tension" by staging a new round of joint military drills with neighbouring South Korea.
Pyongyang, which recently resumed missile tests following stalled talks with Washington, sees the military exercises in the South as preparation for an invasion.
North Korea has defiantly told UN disarmament talks that the exercises by allies US and South Korea could drive Pyongyang to "reconsider the major steps we have taken so far".
A North Korean official said of the drills: "They can neither conceal nor whitewash its aggressive nature in any manner."
The official added: "The United States is inciting military tension hostile to the DPRK by deploying a large amount of latest offensive military hardware in South Korea in disregard of its commitment to suspend joint military exercises made at summit level."
At the summits between Kim Jong-un and Donald Trump, North Korea had agreed to suspend missile and nuclear tests.
However, it has launched a number of missiles and rockets since talks at the second summit, held in Hanoi, Vietnam, in February. broke off.
The US is pushing for North Korea to abandon its nuclear weapons programme, and Pyongyang is asking for crippling sanctions to be lifted.
Earlier, US Defence Secretary Mark Esper said Washington will not overreact to a series of missiles launches by North Korea in recent weeks and would keep the door open to talks with Pyongyang.
North Korea fired missiles into the sea off its east coast for the fourth time in less than two weeks, the South Korean military said on Tuesday, as Pyongyang protested that joint U.S.-South Korea military drills violated diplomatic agreements.
Esper told reporters travelling with him to Japan: "The key is to keep the door open for diplomacy... we're not going to over react to these, but we monitor them, we watch them closely and we're cognisant of what's happening."
He added that the missiles launched on Tuesday were short-range ballistic ones and he would be speaking about North Korea with his counterparts in Japan and South Korean during his upcoming visit to both countries, Reuters reported.
Trump and Kim met on June 30 at the heavily fortified demilitarised zone (DMZ) which divides the Koreas.
Since then Pyongyang has accused Washington of breaking a promise by planning the military exercises and warned the drills could derail talks.
Trump has denied the claims.
Esper said the current exercise with South Korea, known as Dong Maeng and largely computer simulated, was underway and at this point there was no plan to alter future joint military drills with Seoul.
