Ukrainian President Volodymyr Zelenskyy has replaced his minister of defence, Oleksii Reznikov.
The dismissal is not unexpected, but it does come amid a major Ukrainian offensive. President Zelenskyy has named Rustem Umerov to replace Reznikov, an experienced participant in peace talks with Russia.
He was a key figure in last year's negotiations to ensure the safe export of Ukrainian grain.
Luke Harding has been covering this story from London.
Harding spoke to Corin Dann.