The Trump administration has begun the year with an open and reckless threat of nuclear war against North Korea—a conflict that would inevitably drag in other nuclear-armed powers, with catastrophic consequences for the world.

In a New Year’s speech, North Korean leader Kim Jong-un offered talks with South Korea to ease tensions on the Korean Peninsula but warned the US he was ready to defend North Korea. The entire US mainland, he declared, was “within the range of our nuclear weapons and the nuclear button is always on the desk of my office.”

US President Donald Trump fired off a derogatory and provocative tweet: “Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!”

The remarks further inflame an extremely tense situation and undermine the meeting between North and South Korea scheduled for next Tuesday. In an earlier tweet, Trump was decidedly cool toward the prospect of such talks, saying: “Perhaps that is good news, perhaps not—we will see!”

White House press secretary Sarah Sanders faced hostile questioning over Trump’s tweet, with one journalist asking: “Should Americans be concerned about the President’s mental fitness that he appears to be speaking so lightly about threats regarding a nuclear button?”

Sanders responded by questioning North Korean leader Kim’s mental fitness, then aggressively defending Trump’s threat. “This is a president,” she declared, “who’s not going to cower down and he’s not going to be weak, and is going to… stand up and protect the American people.”

Sanders attacked the previous Obama administration for failing to tackle North Korea and declared that the Trump administration was going to continue its strategy of “maximum pressure” on the Pyongyang regime. Trump has insisted he will not allow North Korea to build a nuclear missile capable of reaching continental America and will, if necessary, use military force to prevent it.

Trump came under fire from several congressional Democrats, with Ro Khanna calling for new legislation restricting the president’s ability to launch a pre-emptive nuclear strike without authorisation. Jim Himes expressed the fear that Trump’s tweet could result in a fatal miscalculation with North Korea, warning: “That would get real very quickly.”

These reactions reflect sharp divisions in ruling circles in Washington over Trump’s confrontational policies toward North Korea and China, which have produced mounting calls for the president’s removal.

“This Tweet alone is grounds for removal from office under the 25th Amendment. This man should not have nukes,” Richard Painter, a lawyer who worked for President George W. Bush, commented. Under the 25th amendment, the vice-president and a majority of the cabinet can dismiss a president deemed to be unfit to hold office.

The bitter factional disputes in Washington are tactical in character. The political establishment as a whole has backed a succession of criminal wars of aggression over the past 25 years and would not hesitate to back the use of nuclear weapons to defend US economic and strategic interests. Those opposed to Trump, however, view Russia rather than China as the most immediate threat to be dealt with.

Trump’s bellicose threats to use the huge US nuclear arsenal are not just aimed at North Korea. They are designed to send a warning to any country that poses a challenge to American global hegemony. Trump has continued President Barack Obama’s “pivot to Asia” against China that includes a huge military build-up in the Asia Pacific region in preparation for war.

The Trump administration has exploited the supposed North Korean threat to justify huge joint military exercises with South Korea and pressure China to impose crippling sanctions on the Pyongyang regime. The Chinese leadership is clearly concerned at the danger of war, including nuclear war, in its backyard, but also reluctant to provoke a crisis in North Korea that could be used to install a pro-US regime in Pyongyang.

An editorial in the state-owned Global Times yesterday expressed alarm at Trump’s tweet, declaring that “vying for who has a bigger, more powerful nuclear button is definitely not a solution” to the confrontation.

The editorial warned that the standoff on the Korean Peninsula could not continue. “It will get better, or get worse. If there is no major turnaround, a horrible situation might not be so far away,” it stated. The Trump administration has repeatedly rejected Chinese proposals for negotiations with North Korea.

The terrible scale of destruction that even a limited war on the Korean Peninsula, or restricted nuclear exchange, was outlined in a lengthy essay entitled “The Korean Missile Crisis: Why Deterrence Is Still the Best Option” in the November/December issue of Foreign Affairs.

The author Scott Sagan, who is highly critical of Trump, warned that the current confrontation with North Korea was more dangerous than the 1962 Cuban missile crisis, during which the world teetered on the brink of nuclear war. He argued for a policy of containment and deterrence of a nuclear-armed North Korea, akin to US strategy during the Cold War.

The alternative, Sagan explained, would be horrendous. “According to NUKEMAP, a single 100-kiloton nuclear weapon detonated above the port city of Busan, in South Korea… would kill 440,000 people in seconds. A weapon of that size detonated over Seoul would kill 362,000; over San Francisco, the number would be 323,000.” These estimates did not include deaths from fires and nuclear fallout.

A nuclear war would kill millions, even if it did not involve other nuclear-armed powers such as Russia and China. Yet that is exactly what Trump is threatening. Using the United Nations as a world stage last year, he belligerently declared he would “totally destroy” North Korea if it posed a threat to the US.

Sagan’s assessment was echoed this week by the former chairman of the US Joint Chiefs of Staff, Admiral Mike Mullen, who warned that the world was “closer, in my view, to a nuclear war with North Korea and in that region than we have ever been.” Mullen was pessimistic about any peaceful solution, saying: “I don’t see the opportunities to solve this diplomatically at this particular point.”