Britain has called on Russia to free detained Ukrainian pilot Nadia Savchenko and says it will not be intimidated by President Vladimir Putin's "saber-rattling."
Savchenko, who has become a symbol of resistance in Ukraine to Russian aggression, is being held in Moscow on charges of aiding the killing of two Russian journalists in east Ukraine last year.
She has been weakened by a hunger strike against what she says are politically motivated charges.
British Europe Minister David Lidington told Savchenko in a letter London was pressing Moscow for her release.
"During 12 months of incarceration you have shown immense courage and resilience," he wrote, calling on Russia to live up to its international commitments.
Separately, while visiting Estonia, British Defense Minister Michael Fallon criticized Putin for his plan to add intercontinental ballistic missiles to Russia's nuclear arsenal.
"This is clearly saber-rattling clearly designed to provoke, designed to intimidate. It won't do that," Fallon said. "We are prepared to modernize our defenses and do whatever is necessary to reassure as well as to deter."