The American-made interceptors are the only effective weapon for downing Russia's ballistic missiles.

The cyber-attack, which the company describes as complex, is believed to be the largest ever of its kind.

It is Pike's first public statement since she survived an execution attempt by lethal injection in September.

Hundreds of people are also understood to have stayed in the front-line town, despite the dangers.

The escalation came after the government suspended two senior justices and moved to bring criminal charges against them.

Novaya Gazeta has been one of the most high-profile independent news outlets in Russia over the last three decades.