A joint search operation was launched by the Government Railway Police (GRP) and Railway Protection Force (RPF) at various railway stations here, after Pakistan-based terror outfit Jaish-e-Mohammed (JeM) threatened to target railway stations in Punjab and Rajasthan, reports New Indian Express on April 19.The letter was sent to the Punjab Railway Board Manager by the JeM's ‘area commander’ Masoor Ahmed on April 18.