The two men, who wore blue and yellow ribbons in the colours of Ukraine’s flag, laid bouquets of sunflowers, the country’s national emblem, in front of the Catholic Church of Saints Volodymyr and Olha before taking a moment to reflect.

The initiative aimed to show their “solidarity with the people of Ukraine” after Russia launched a war against its neighbour last month, according to a video of the visit posted on Clinton’s Twitter account.

“America stands united with the people of Ukraine in their fight for freedom and against oppression,” the tweet said.

That sets the 42nd and 43rd US presidents apart from Donald Trump, the 45th president, who just before the invasion described Vladimir Putin’s strategy of amassing troops on Russia’s border with Ukraine and then recognising the independence of two pro-Russian separatist territories as a stroke of “genius”.