North Korea has carried out a total of five nuclear tests so far, and according to an expert satellite imagery analysis Pyongyang may be preparing for a sixth test soon.
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. That raised questions about US President Donald Trump's plans for North Korea, which has conducted several missiles and nuclear tests in defiance of United Nations and unilateral sanctions.
American intelligence officials have reportedly said the United States is ready to launch a preemptive strike with conventional weapons against North Korea if it is sure Pyongyang is about to stage another nuclear weapons test.
North Korea responded by warning of a "merciless retaliatory strike" if the US acts first.
State television showed what appeared to be several KN-08 missiles rolled out on trucks at the parade. An official from South Korea's Defense Ministry couldn't immediately confirm whether any of the rockets represented a new type of ICBM.
Those missiles rolled out first at the parade, along with other weaponry that North Korea has previously shown off.
The hardware displayed Saturday included what appeared to be new ICBMs or prototypes, and the Pukkuksong submarine-launched ballistic missile, which Pyongyang successfully test-fired last August, reports and analysts said.
Choe Ryong Hae, a close aide to Kim Jong Un, made a speech at the parade, saying the country is ready to stand up to any threat posed by the United States.
But now Pyongyang has threatened an "annihilating strike" if Trump "wages reckless provocation against us".
Other military hardware at the parade included tanks, multiple rocket launchers and artillery, as well as a solid-fuel missile created to be fired from submarines.
A surprise at the parade was the appearance of Kim Won Hong, who was among the senior government officials joining Kim Jong Un at the podium.
Other senior officials joining Kim at the podium included Kim Won Hong, who the South Korean government had said earlier this year was sacked from his job as state security minister, presumably over corruption.
China is seeking Russia's help to cool surging tensions over Pyongyang's nuclear ambitions, the country's foreign minister has told his Moscow counterpart, after Beijing warned of possible conflict over North Korea. South Korea has a spotty record of tracking developments in North Korea, as information about the secretive, authoritarian state is often impossible to confirm. The country under his watch has been aggressively pursuing a goal of putting a nuclear warhead on an ICBM capable of reaching the continental United States.
"Our toughest counteraction against the US and its vassal forces will be taken in such a merciless manner as not to allow the aggressors to survive", the military statement said, according to the North's state-sponsored KCNA news agency. The North also a year ago launched a long-range rocket that put a satellite into orbit, which Washington, Seoul and others saw as a banned test of missile technology.
Asian shares mixed as Trump talks down US dollar
If it remains a habit, US efforts to stop other countries from pursuing similar strategies could be undermined. Asian stock markets were mostly lower Thursday after Wall Street fell for a second day and U.S.