|U.S. Air Force B-1B Lancer bombers flying with F-35B fighter jets|
Ri Yong Ho told reporters in New York: "The whole world should clearly remember it was the US who first declared war on our country.
"Since the United States declared war on our country, we will have every right to make countermeasures, including the right to shoot down United States strategic bombers even when they are not inside the airspace border of our country."
North Korea's Foreign Minister spoke at the UN on Saturday
The Pentagon responded with its own threat, saying that if North Korea did not stop its provocative actions, it will make sure the "President is provided with options to deal with Pyongyang."
|North Korea's Foreign Minister spoke at the UN on Saturday|
"We have not declared war against North Korea and frankly the suggestion of that is absurd," said White House press secretary Sarah Huckabee Sanders.
Kim Jong Un is determined to build nuclear weapons
Mr Ri, who made his remarks before leaving New York following last week's UN General Assembly, added: "In light of the declaration of war by Trump, all options will be on the operations table of the supreme leadership of the DPRK (Democratic People's Republic of Korea)."
"The question of who won't be around much longer will be answered then," he said.
He was referring to the US President's tweet late on Saturday: "Just heard Foreign Minister of North Korea speak at U.N. If he echoes thoughts of Little Rocket Man, they won't be around much longer!
|Trump gives N Korea threat in UN speech|
"Just heard Foreign Minister of North Korea speak at U.N. If he echoes thoughts of Little Rocket Man, they won't be around much longer!4:08 AM - Sep 24, 201748,474 35,534 127,377 Donald J. Trump@realDonaldTrumpLast week, in his first speech to the General Assembly, Mr Trump vowed to "totally destroy" North Korea if it continued to threaten the US and it allies.
The latest escalation in the war of words between the nations came two days after US Air Force bombers, escorted by fighter jets, flew over waters east of North Korea on Saturday.
The Pentagon called it a "show of force" designed to show the range of military options available to President Trump.
On Sunday, the insults continued to fly, as Mr Ri labelled Mr Trump a "mentally deranged megalomaniac".
Tensions have been growing as Pyongyang has continued to develop nuclear weapons in the face of worldwide demands that it cease.
In recent weeks the reclusive state detonated its sixth nuclear bomb and has test-fired intercontinental missiles, claiming it needs to defend itself against hostility from the United States and its allies.