Vladimir Putin has reportedly been forced to cancel the upcoming Victory Day parade in Crimea, just days after a Ukrainian sea drone destroyed a Russian fighter jet worth €41 million. The celebration was scheduled to take place on May 9 in the city of Sevastopol,

The apparent cancellation has raised fresh questions about the Kremlin's ability to secure key sites, even deep inside occupied territory.

World affairs editor Sam Kiley has been covering Ukraine since the Russian invasion of 2014. Here he looks at the current state of the conflict, the likelihood of a lasting ceasefire and what Russian