Jammu and Kashmir Director General of Police (DGP) Dilbag Singh, on Wednesday, had directed officers to augment security and keep a vigil on suspicious elements along the Jammu-Srinagar national highway. Singh had ordered the surveillance during his visit to the Amarnath Yatra camps along the highway, ahead of the upcoming pilgrimage for seamless conduction to the 3,880-meter-high holy cave shrine of Amarnath in the south Kashmir Himalayas.