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.

"I like the concept of a ceasefire for one reason, because you'd stop killing people immediately... But we can work a deal where we're working on a peace deal while they're fighting." President Trump walked back on his previous comments where he suggested "severe consequences" for Russia if Russian President Vladimir Putin didn't agree to a ceasefire before a meeting with Ukrainian President Volodymyr Zelenskyy and other European and NATO leaders.