President Donald Trump was not phased by Russian President Vladimir Putin opting not to attend peace talks with Ukrainian officials in Turkey, saying he did not expect Putin to go if he was not there.

Russia's Vladimir Putin spurned a challenge to meet face-to-face with Volodymyr Zelenskiy in Turkey on Thursday, instead sending a second-tier delegation to planned peace talks, while Ukraine's president said his defence minister would head up Kyiv's team.