(reuters) -- Ri Yong Ho said a Twitter message by Trump on Saturday, in which the president warned that the minister and North Korean leader Kim Jong Un “won’t be around much longer” if they acted on their threats, amounted to a declaration of war.

White House spokeswoman Sarah Sanders on Monday denied the United States had declared war, calling the suggestion “absurd”.

Speaking earlier in New York, where he had been attending the annual U.N. General Assembly, Ri told reporters: “The whole world should clearly remember it was the U.S. 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.

“The question of who won’t be around much longer will be answered then,” Ri added.

On Saturday, U.S. Air Force B-1B Lancer bombers escorted by fighters flew east of North Korea in a show of force after a heated exchange of rhetoric between Trump and Kim over North Korea’s nuclear and missile programs.

“That operation was conducted in international airspace, over international waters, so we have the right to fly, sail and operate where legally permissible around the globe,” Pentagon spokesman Colonel Robert Manning said on Monday.

North Korea, which has remained technically at war with the United States since the 1950-53 Korean War ended in a truce and not a peace treaty, has been working to develop nuclear-tipped missiles capable of hitting the U.S. mainland and conducted its sixth and largest nuclear test this month.

(Photo: Foreign Minister Ri Yong-ho of North Korea outside the United Nations in New York on Monday.CreditRichard Drew/Associated Press)