The Foreign Office says Britain has imposed sanctions against six people who led the penal colony where Russian opposition leader Alexei Navalny died last week. The six prison officials will be barred from traveling to Britain, and any assets they may have in the United Kingdom will be frozen. The Foreign Office says Navalny was denied medical treatment and was forced to walk in temperatures dropping to minus 32 degrees Celsius. The anti-corruption campaigner also was held in solitary confinement. The British foreign secretary says “it’s clear that the Russian authorities saw Navalny as a threat and they tried repeatedly to silence him.”