Joe Biden declared on Wednesday that a North Korean nuclear attack on his country or South Korea would spell doom for Pyongyang. Under a new agreement between Washington and Seoul, the US would respond to such an attack with nuclear weapons, South Korean President Yoon Suk-yeol added.

“A nuclear attack by North Korea against the United States or its allies or partners is unacceptable and will result in the end of whatever regime were to take such an action,” Biden told reporters at the White House.

Speaking alongside Biden, Yoon declared that “sustainable peace on the Korean peninsula does not happen automatically.” “We can achieve peace through the superiority of overwhelming forces and not a false peace based on the goodwill of the other side,” Yoon said, adding that in the event of a nuclear attack from the north, the US and South Korea would “respond swiftly, overwhelmingly and decisively using the full force of the alliance, including US nuclear weapons.”

Biden’s words echo those of his predecessor, Donald Trump, who in 2017 warned North Korea that he would respond with “fire and fury like the world has never seen” if the country threatened the US with nuclear weapons. Although the north tested a nuclear bomb a month later, Trump and North Korean leader Kim Jong-un agreed to a detente and went on to meet several times, and the north’s missile tests came to a halt for most of Trump’s remaining time in office.

These tests have since restarted and ramped up. Pyongyang has test-fired more than 100 missiles since the beginning of 2022, and this month tested its first solid-fuel intercontinental ballistic missile and a nuclear-capable underwater attack drone. Officials in Washington and Seoul have claimed since last year that the north is gearing up for its seventh underground test of a nuclear weapon.