MOSCOW, Aug. 10 -- Russia's Federal Security Service said Monday it had detained a Russian citizen in the Kherson region who had been recruited by Ukrainian military intelligence to carry out an attack on Russian servicemen, with the suspect allegedly planning to use a modified powerbank as a concealed explosive device.

The FSB identified the suspect as a man born in 1976, detained in the city of Skadovsk in the Kherson region. According to the security service, the individual had been recruited through the Telegram messaging application by Ukrainian intelligence handlers, who tasked him with placing the explosive-laden device to kill or injure Russian military personnel stationed in the area.

The powerbank, a consumer electronics item ...