The terrorists who carried out the attack on the Sunjuwan Army camp had infiltrated into India in July 2017, sources say.
According to preliminary investigation of the Army, the three terrorists were hiding in various parts of Jammu and Kashmir since July and were looking at carrying out an attack.
Six Army personnel and a civilian were killed in the attack on the Sunjuwan military station on February 10. Three JeM terrorists, who carried out the strike, were killed during the gun battle with the Army.
The JeM terrorists who carried out the attack had crossed over to India from Pakistan in July last year when infiltration had gone up, the sources said.
They said a detailed investigation is being carried into the Sunjuwan attack and the probe report will be examined by top echelon of the Army.
The sources said immediate steps are being taken to ensure that such attacks do not recur.
The attack on the camp came days after four Army men were killed in Pakistani firing in Rajouri district of Jammu and Kashmir.
Army sources said full freedom has been given to local commanders of the Army along the Line of Control in Jammu and Kashmir to effectively retaliate any act of violence by Pakistani troops.
Following the attack on the Sunjuwan military station in Jammu, Defence Minister Nirmala Sitharaman warned Pakistan saying the neighbouring country "will pay for its misadventure".