An enraged President Trump, surrounded by uniformed military leaders, used the same press conference last week to condemn a raid on the office of his personal attorney, Michael Cohen, and announce that he was ‘making a decision as to what we do with respect to the horrible attack that was made near Damascus’. ‘In our world,’ Trump said, ‘we can’t let atrocities like we all witnessed’ happen, and ‘because of the power of our country – we’re able to stop it.’ That is the image, and the language, it will be necessary to keep in mind during the coming months if we are to understand the relationship between domestic crisis, foreign relations, the rule of law, military force, authoritarian populism and visual culture that is poised to reshape the international order.

Most international lawyers agree that the missile strikes against Syria at the weekend were illegal. Few governments other than those of the US, the UK and France have ever seriously proposed that international law allows hegemonic states to use force to police weapons conventions, punish criminals or pursue humanitarian objectives without Security Council authorisation. This is not because the majority of the world’s leaders are evil monsters or the majority of the world’s peoples passive dupes, but because the moral certainties and civilising missions of heavily armed hegemonic states continue to represent a significant global threat to peace, security and humanity.

Yet many of the same liberal establishment figures who decry Trump’s undermining of the rule of law and democratic political institutions in the US have again celebrated his resort to force in Syria. This is a symptom of a broader pattern of dualistic thinking about the relation between domestic and international politics. For decades, liberal internationalists have maintained a commitment to the rule of law domestically, but urged their governments to abandon the UN Charter rules governing the use of force. They have developed novel legal interpretations explaining why new forms of intervention to protect civilians, fight terrorists and secure vital resources are not only necessary but righteous. They are convinced that the means of undermining international law is justified by the ends of a liberal international order, and that it will be possible to quarantine the undermining of law internationally from the undermining of law domestically.

For the people of Syria, and of any state in which foreign intervention has somehow come to seem normal rather than scandalous, the division between a domestic and an international rule of law has long been non-existent. Syria, like Afghanistan, Nicaragua, Vietnam and numerous other states before it, has become the devastated site of proxy wars between great powers. For many newly independent states during the 1960s and 1970s, it was already clear that, while the UN Charter prohibited the resort to force as a tool of foreign relations, it would be far more difficult to restrain major powers from engaging in proxy wars. The consolidation of international legal principles to prevent new forms of intervention in civil wars and to respect sovereign equality was seen as a necessary condition for meaningful self-determination. The consequences of violating those hard-fought principles, and the dangers of the unrestrained militarisation of civilian life, can be seen from the situation in Syria, where an internationalised civil war raging since 2011 has resulted in more than 450,000 killings, 5.4 million Syrians registered as refugees in neighbouring states, and the destabilisation of the entire region.

The illusory nature of a division between the commitment to law domestically and internationally is now also becoming clear in the US, as the tableau of Trump and his military advisers shows. Trump has taken up the language of red lines to threaten not only Bashar al-Assad (‘When our president draws a red line, our president enforces a red line,’ the US ambassador to the UN, Nikki Haley, announced), but also Robert Mueller. Trump described the raid on his lawyer’s office (duly authorised by warrants) as an ‘attack on our country’. He did so while surrounded by the military leaders of, as he put it, ‘the greatest fighting force ever’. He claims for himself the right to decide where and when the rule of law begins and ends. The challenge to democracy that this approach to the law represents is clear domestically. Trump’s presidency is now revealing to liberal audiences why it also matters internationally. Unless that challenge can be resisted, a world in which an authoritarian leader surrounded by military advisers dictates the limits of the law will be the world in which the US, its allies and its enemies will have to exist for years to come.