Security has been intensified across Ayodhya, Varanasi and Mathura after a threatening email warned of bomb attacks at key religious sites and schools between November 8 and November 27, triggering a multi-agency investigation and heightened vigil in the three sensitive cities. Bomb threat email sent to Ayodhya court triggers high alert in Ayodhya, Varanasi and Mathura; police, cyber teams probe source and tighten security Nov 8-27.