Russian opposition activist Alexei Navalny is no longer in a medically induced coma and his condition has improved, German doctors said Monday, more than two weeks after he was poisoned with a nerve agent.

The German government said Navalny was poisoned with Novichok, a substance developed by the Soviet military during the Cold War. Pressure has mounted on the Russian government to explain how one of its fiercest critics came to be sickened with a military-grade neurotoxin, becoming seriously ill while on a flight from Siberia to Moscow last month.

Navalny “has been removed from his medically induced coma and is being weaned off mechanical ventilation,” said a statement from Berlin’s Charité hospital, where Navalny was moved after pressure from his family and supporters who said he was not safe in Russia.

Read more at NBC News.