The claim that America is a “threat to world peace” has been a staple of Russian and Iranian propaganda for many years. For believers in the western alliance, it is painful to acknowledge that there is now some truth to this idea. Under Donald Trump, America looks like a dangerous nation.

Over the past week, Mr Trump has indulged in nuclear brinkmanship in North Korea, issued vague threats of military action in Venezuela and flirted with white supremacists at home. He is offering the very opposite of the steady, predictable and calm leadership that American allies seek from Washington.

Mr Trump’s swiftly notorious threats that North Korea risks “fire and fury” from a “locked and loaded” America were particularly irresponsible. Even if the threat is a bluff, it puts American credibility on the line and risks triggering escalation from the Kim Jong Un regime, which is threatening to fire missiles near the US territory of Guam. Even more alarming, the Trump administration is openly flirting with the idea of a pre-emptive strike on North Korea - arguing that a nuclear-armed Mr Kim cannot be deterred. But if America could rely on deterrence to contain the nuclear threat from Stalin’s Russia and Mao’s China - it can certainly do the same with Mr Kim’s North Korea. All previous presidents have rejected the idea of pre-emptive attacks on nuclear-armed states - for obvious reasons.

The international crisis that Mr Trump is stoking is increasingly inseparable from the domestic problems besieging his administration. The investigation by former Federal Bureau of Investigation director Robert Mueller into Russian intervention in the US election is getting ever closer to the president’s inner circle. Congress is deadlocked and the White House is a merry-go-round of sackings and scheming. And now there is political violence on the streets, as white supremacists and neo-Nazis attack, and even kill, protesters in Charlottesville - while the president issues evasive and equivocal statements from a golf course.

The danger is that these multiple crises will merge, tempting an embattled president to try to exploit an international conflict to break out of his domestic difficulties. Just this week, Sebastian Gorka, a controversial White House aide, used the North Korean crisis to pressure Mr Trump’s domestic critics to back down, telling Fox News: “During the Cuba missile crisis we stood behind JFK. This is analogous to the Cuba missile crisis. We need to come together.”

‘Alarm bells’

Mr Gorka’s flirtation with the idea that the threat of war could lead Americans to rally around the president should sound alarm bells for anyone with a sense of history. Governments facing a domestic crisis are often more inclined to adventurism abroad. For example, the German government that led Europe into the first world war felt under acute threat from domestic political enemies. But on the day war broke out, an exultant Kaiser told a crowd: “I no longer recognise any parties or affiliations; today we are all German brothers.” Or as Mr Gorka put it last week: “These are the moments when we have to come together as a nation.”

Leaders under severe domestic political pressure are also more likely to behave irrationally. During the Watergate crisis, members of Richard Nixon’s cabinet told the military to double check with them before obeying a presidential order to stage a nuclear strike. Unfortunately, it is not clear that any US official - now or then - has the right to countermand the president if he decides to go nuclear.

Outside observers are left hoping that the “adults” in the Trump administration will somehow manage the president. But, at least in public, the pushback against Mr Trump’s threats of war has been remarkably weak, both in Congress and within the administration.

HR McMaster, the president’s national security adviser, has defended Mr Trump’s warmongering on national television. Meanwhile, General McMaster himself is under attack from the white nationalist wing of the president’s supporters, who blame him for sacking some of their allies on the National Security Council. Last week, as the North Korean crisis built, the hashtag “Sack McMaster” was trending on Twitter, as the nationalists sought to purge their newfound enemy from the White House. This is the very opposite of the atmosphere that should prevail in the White House as a potential nuclear confrontation looms in the Pacific.

Those who are hoping that America’s “Deep State” will contain Mr Trump - or even force his resignation - are probably guilty of wishful thinking. Forcing him from office remains a massively difficult task and risks provoking a further radicalisation both in domestic politics and the conduct of US foreign policy.

A final disturbing thought is that Mr Trump’s emergence increasingly looks like a symptom of a wider crisis in American society, that will not disappear, even when Mr Trump has vacated the Oval Office. Declining living standards for many ordinary Americans and the demographic shifts that threaten the majority status of white Americans helped to create the pool of angry voters that elected Mr Trump. Combine that social and economic backdrop with fears of international decline and a political culture that venerates guns and the military, and you have a formula for a country whose response to international crises may, increasingly, be to “lock and load”.

Gideon Rachman is an FT columnist

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