NEW DELHI: In a major counteroffensive after Pakistan's unprovoked firing, the Indian Army on Sunday carried out heavy artillery strikes targeting four terror launch pads and several Pakistani military positions in Neelam Valley in Pakistan-occupied-Kashmir, killing at least six Pakistani soldiers and reportedly eliminating a sizeable number of terrorists, government sources said.The Indian retaliation came a day after Pakistan military resorted to unprovoked firing in Tangadhar sector along the Line of Control in which two Indian Army personnel and a civillian were killed. Three others were also injured in the attack, the sources said.They said the four terror launch pads in Neelam valley, opposite to the Tangdhar sector of Jammu and Kashmir have been totally smashed in the artillery fire by the Indian Army and that 10-15 terrorists were staying in each of the facilities at the time of the attack, the most significant offensive since India carried out the Balakot strike in February.A highly-placed source, meanwhile, said at least 20 terrorists were killed in the Indian artillery fire, adding the figure may be quite high.The retaliation has caused substantial harm to the terrorist infrastructure across the Line of Control (LoC), Rawat told reporters on the sidelines of an event."So far, as per the information available with us, 6-10 Pakistani soldiers have been killed and nearly as many terrorists," the Army Chief said, adding that more information on terrorist casualty was being obtained."Three terror camps have been destroyed and on the fourth one also, we have caused severe damage," he said.Defence minister Rajnath Singh spoke to Army chief General Bipin Rawat following the Indian offensive and he has been keeping an eye on the evolving situation along the LoC, government sources said.Spokesperson of Pakistan military Major General Asif Ghafoor, in a series of tweets, said a total of five Pakistani civilians were killed in the Indian strikes."Targeting innocent civilians by Indian Army is an attempt to justify their false claims of targeting alleged camps," Ghafoor alleged and also claimed that nine Indian soldiers killed and two Indian bunkers were destroyed by Pakistan army .A senior Indian Army official rejected Ghafoor's allegations and claims.In a statement, the Indian Army said Pakistani army initiated unprovoked cease fire violations to assist infiltration by terrorists into Indian territories in the Tangadhar sector last evening."As a result calibrated escalation of area weapons was undertaken by the Indian side in which terrorist launch pads and several Pakistan army posts giving incidental protection to these launch pads and certain gun positions were hit," it said.It said Indian Army retains the right to respond at a time and place of its choosing in case Pakistan army continues to assist terrorist activities across Indian borders.Sources said Pakistan has been trying to push terrorists into Kashmir to trigger unrest in the wake of India's decision to withdraw Jammu and Kashmir's special status and bifurcate the state into two Union Territories.Soon after government announced its decision to reorganise Jammu and Kashmir on August 5, the Army was put on high alert along the LoC to effectively repulse any possible Pakistani misadventure.The sources said the pounding of Pakistani positions and terror camps cannot in any way be compared to surgical strikes carried out by the Indian Army in September 2016 on terror launch pads across the Line of Control. However, the offensive was the most significant one after India carried out the Balakot strike in February.On February 26, India carried out an aerial strike on a terrorist training camp of the Jaish-e Mohammad terror group in Pakistan's Balakot, in response to Pulwama terror attack in which 40 CRPF personnel were killed.Pakistan Air Force retaliated the next day by trying to target military installations but it was repulsed. The PAF downed a MiG-21 Bison in an aerial combat besides capturing IAF pilot Varthaman, who was handed over to India on March 1. Varthaman had shot down an F-16 of Pakistan before his MiG-21 Bison was hit.