Ukraine's President Volodymr Zelensky has accused Russia of "doing everything it can" to prevent a meeting with Vladimir Putin to try to end the war. US President Donald Trump has sought to bring the two leaders together, but he said on Friday "that's like oil and vinegar... they don't get along too well".

The fast-moving developments in Trump's near-back-to-back summits with the heads of Russia, Ukraine and European powers have highlighted a pair of repeated sticking points.