Associate links move to tycoon with ties to Putin who was among a dozen Russians indicted in 2018 by a US grand jury in the Mueller investigation

But hospital notes it's too early to gauge the 'potential long-term effects' of Russian opposition leader's severe poisoning from nerve agent

Vil Mirzayanov, an ex-Soviet chemist who now lives in the US, was the first to reveal nerve agent in the early 1990s; he says he's sorry he 'took part in this criminal business'

Poisoned opposition leader and Putin critic jokes that breathing without a ventilator is 'strongly recommended'; doctors can't rule out long-term health issues

As international powers press Moscow to quickly investigate alleged poisoning of top Putin rival, Russia rejects 'unfounded attacks'

German hospital treating Alexei Navalny says he is 'responding to verbal stimuli,' but it's too early to gauge 'potential long-term effects of his severe poisoning'

Spokesman pushes back against claim Moscow was responsible for attack on Putin critic; Merkel refuses to rule out consequences for Baltic Sea pipeline as part of possible sanctions

NATO says there's 'proof beyond doubt' that Russian opposition leader was given Novichok; US president says nuclear arms negotiations with Moscow more important than anything

Calls mount for international action after Germany confirms traces of nerve agent Novichok in hospitalized Putin critic

Merkel's spokesman says testing shows same chemical used to poison former Russia spy Sergei Skripal and his daughter was detected in Alexei Navalny