After dangling the possibility of his attendance, Trump says he will stay away but still wants to meet with Putin, further weakening the Istanbul talks.

Ukraine will make securing a ceasefire a priority in expected talks with a Russian delegation in Istanbul on Friday, a Ukrainian diplomatic source said, adding there was also a need for "confidence-building measures".

Ukraine decided to send a delegation to Istanbul, despite the low level of the Russian delegation. Meanwhile, Russia may be preparing a new offensive. Read more about what happened on Thursday, May 15.