North Korean Foreign Minister Ri Yong Ho on Monday accused the United States of declaring war on the country. He said Pyongyang had the right to take measures against the threat, Reuters reported.

“Since the United States declared war on our country, we have every right to take countermeasures, including the right to shoot down United States strategic bombers even when they are not inside the airspace border of our country,” he was quoted as saying.

“The whole world should clearly remember it was the United States who first declared war on our country,” the foreign minister told reporters in New York.

He made the comments amid escalating tension between the two nations. On Sunday, US bombers had flown in international airspace over the waters east of North Korea to demonstrate the range of military options available to President Donald Trump.

Last week, in his first address to the United Nations General Assembly, Trump had called leader Kim Jong-un a “rocket man” on a “suicide mission,” prompting the North Korean leader to warn the US president that he would “pay dearly” for his threat.

The North Korean threat has dominated this year’s gathering of world leaders at the United Nations, amid fears that the heated rhetoric with the US could trigger a war. Pyongyang has stepped up its development of weapons, testing a string of missiles this year. North Korean state media had on September 3 claimed that they had successfully conducted a hydrogen bomb test. This was the country’s sixth underground nuclear test since 2006.