"The whole world should clearly remember it was the US who first declared war on our country," Ho, who is here to attend the annual UN General Assembly Session, told reporters.
"Since the US declared war on our country, we will have every right to make countermeasures, including the right to shoot down US strategic bombers even when they are not inside the airspace border of our country," he added.
Tensions have dramatically risen on the Korean peninsula after North Korea early this month conducted its biggest nuclear test, which its state-run KCNA news agency described as a hydrogen bomb.
US President Donald Trump and North Korean leader Kim Jong-Un have traded increasingly threatening and personal insults as Pyongyang races towards its goal of developing a nuclear-tipped missile capable of reaching the US.
More From This Section
Trump on Saturday warned North Korea, saying if the country's foreign minister was echoing thoughts of his supreme leader Kim Jong-Un in his threatening speech at the UN, "they won't be around much longer."
Responding to Trump's tweet, the top North Korean diplomat said the question of "who won't be around much longer will be answered then."
Ro had attacked Trump at the UN General Assembly, deriding him as a "mentally deranged" leader whose threats had increased the chances of military confrontation.