Week-ending 25 September 2020
On 22 September 1999 a suspicious device similar to those used in the recent bombings in Moscow was found and defused in an apartment building in Ryazan. According to reports, local police tested the material on-site and obtained a positive reading for Hexogen (also known as RDX). On 23 September, Vladimir Putin praised the vigilance of the inhabitants of Ryazan and ordered the air bombing of Grozny, which marked the beginning of the Second Chechen War. Three FSB agents who were identified as having planted the devices in Ryazan were arrested by local police. On 24 September 1999, head of the FSB, Nikolai Patrushev announced the incident in Ryazan had been a training exercise and the device found had contained only sugar.
Source: ‘Russian Apartment Bombings,’ Wikipedia
Among other sources, see also: ‘September 1999 Russian apartment bombings timeline,’ The Fifth Estate, 8 January 2015