The North Korean foreign minister's statement that the United States has declared war on Pyongyang is "absurd," the White House said on Monday.

"We've not declared war on North Korea. Frankly, the suggestion of that is absurd," White House spokeswoman Sarah Sanders told reporters. 

North Korean Foreign Minister Ri Yong Ho had claimed that a tweet by U.S. President Donald Trump on Saturday was a declaration of war.

Speaking in New York, the foreign minister said that Pyongyang reserved the right to take countermeasures, including shooting down U.S. strategic bombers even if they are not in the country's air space.