Several US military bases in Europe have been placed on high alert due to the threat of terrorist attacks on US military personnel or facilities, reports CNN. According to two US officials, whose names CNN did not disclose, US military bases were put on high alert over the weekend. Their level of protection was raised to the second highest. Among the bases that have raised their readiness level to Charlie status is the US Army garrison in Stuttgart, Germany, where the headquarters of the US European Command is located. As CNN explains, Charlie status is introduced when an incident occurs or in…