The US Embassy in Russia has warned that extremists had plans for an attack in Moscow and this comes hours after Russian Security Services said that they had filed a planned shooting at a synagogue by a cell from the Afghan arm of Islamic State well the embassy through its website urged all US Citizens to leave Russia immediately and added that people should avoid concerts and crowds and be aware of their surroundings however it gave no further details about the nature of the threat us allies including Britain Canada South Korea and lva have repeated the US warning and have told their citizens not To travel to Russia the warning came several hours after Russia's Federal Security Service which is the main successor to the Soviet era KGB which said that it had filed an attack on a synagogue in Moscow by a cell of the militant group Islamic State the FSB said that the cell was operating in Russia's kuga region as part of the Afghan arm of the group the group is known as Isis Corasan