Three Russian scientists who have worked on hypersonic missile technology face "very serious accusations" of state treason, the Kremlin says.
Colleagues of Anatoly Maslov, Alexander Shiplyuk and Valery Zvegintsev this week published an open letter in their defence, warning that the prosecutions threaten to damage Russian science.
The three men were all leading academics at the Khristianovich Institute of Theoretical and Applied Mechanics (ITAM) in Novosibirsk, the largest city in Siberia. Here's what we know about them.
