"I will not dignify any event that disrespects our soldiers... or our national anthem." So said Mr Mike Pence, the US Vice-President, after walking out of an American football match last month - when some players had "taken a knee" during the playing of The Star Spangled Banner.
The Trump administration's row with high-profile athletes might seem like an "only in America" moment. But similar arguments about national anthems are taking place in China, India and Europe.
These anthem rows are a symptom of a global ideological struggle between nationalists and internationalists. In the US, China and India, the militant defence of national hymns is justified by the new nationalists as simple, healthy patriotism. But a shrill focus on national anthems also has a disturbing side - since it often goes hand in hand with illiberalism at home, and aggression overseas.
Earlier this month, China's National People's Congress passed a law, making "insulting" the country's national anthem an offence, punishable by up to three years in prison. The move is part of a growing vogue for displays of patriotism in China, as part of what President Xi Jinping calls the "great rejuvenation" of his people. It also reflects rising tensions between the government of mainland China and semi-autonomous Hong Kong. At recent football matches in Hong Kong, the Chinese anthem has been booed by anti-Beijing protesters.
The Indian version of this dispute was triggered by a Supreme Court ruling last year, directing that the national anthem be played before any film shown in a public theatre. Supporters of the ruling argue that the anthem is an important glue in a multi-religious country that speaks hundreds of languages.
Indian liberals worry that it reflects a rise in intolerant nationalism under Prime Minister Narendra Modi - which is making life tougher for religious minorities and critics of the government. They also point to incidents of vigilantism in which cinema-goers who failed to rise for the anthem have been attacked.
A different kind of anthem controversy took place in France when Mr Emmanuel Macron celebrated his election victory in May. The background music when the new President strode on stage was not the Marseillaise but Beethoven's Ode To Joy - the European Union's anthem. This was a deliberate rebuke to his defeated opponents in the nativist and anti-EU National Front.
The fact that Mr Macron and Mr Donald Trump have taken very different positions in the anthem rows is significant. For the US and French presidents are currently the two most important spokesmen for rival visions of international politics.
In his speech at the United Nations in September, Mr Trump made the case for an international order based around "strong sovereign nations" - a phrase that he used repeatedly. The US President has also often attacked "globalism", defined by his campaign as "an economic and political ideology which puts allegiance to international institutions ahead of the nation state".
Ten days after Mr Trump's speech, Mr Macron offered a very different world view. In a lecture in Paris, he said: "We can no longer turn inwards within national borders; this would be a collective disaster." The French President saw his enemies as "nationalism, identitarianism, protectionism, isolationism".
It would be easy to assume that Mr Macron's internationalist message has more global support. But the Trumpian vision also has international adherents - from a network of politicians and intellectuals that can be termed the "nationalist international".
In a recent article, Mr Eric Li, a Shanghai-based commentator, argued that Mr Xi's China and Mr Trump's America "have more in common than it appears". Both leaders emphasise national sovereignty and are intent on pushing back against an "overly aggressive, one-size-fits-all universal order".
Mr Li argues that Mr Xi and Mr Trump have many potential soulmates in the anti-globalist camp, including leaders such as Mr Vladimir Putin in Russia, Mr Rodrigo Duterte in the Philippines, Mr Viktor Orban in Hungary, Mr Modi, and Mr Abdel Fattah al-Sisi in Egypt, as well as Britain's Brexiters. It is quite a list - underlining the extent to which nationalism is resurgent.
The new nationalists argue that "strong sovereign nations" should be the basis of a stable, international order that rolls backs the excesses of a utopian and elitist "globalism".
But there is something a little naive about the idea of peaceful coexistence between nationalists. Strongmen leaders may have a shared contempt for international bureaucrats and human rights lawyers. But nationalism is often associated with disdain for the views and interests of foreigners. So, sooner or later, rival nationalisms are liable to come into conflict - and that is particularly the case with the United States and China.
Mr Trump's nationalism is fired by a sense that America is in decline and can recover only by getting tough with the outside world. Mr Xi's nationalism is fuelled by a sense that China is on the rise, and can finally avenge historic humiliations. Those two rival visions could easily lead to US-China clashes in the Korean peninsula, the South China Sea or at the World Trade Organisation.
In his Sorbonne speech, Mr Macron warned that rising nationalism could "destroy the peace we so blissfully enjoy". Sadly, it seems unlikely that anybody in Washington or Beijing was paying much attention.