They also attributed the long period of operation, which has lasted for three days, to strict instructions by Prime Minister Narendra Modi and Defence Minister Manohar Parrikar not to take "unnecessary risks" to avoid casualties.
They added that the effort was also to catch at least one of the terrorists alive, if possible.
Explaining why seven security personnel have been killed, the sources said, "The first five Defence Security Corps personnel were killed when the terrorists attacked a rest room at 3:30 AM where a shift change was happening. Despite that one of the DAC guards killed a terrorist with his own gun before being killed.
The sources maintained that the terrorists' plan to inflict heavy damage to the air force assets, MiG 21 fighter aircraft and Mi 25 attack choppers, stationed at the base had been countered.
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They said that the terrorists were "better trained than the 2008 Mumbai terror attackers".
Asked why the operation has taken so much time, the sources said both Modi and Parrikar had given clear instructions that "unnecessary risks" should not be taken.
They added that the terrorist were carrying AK47s, Under Barrel Grenade Launchers (UBGL), 52 MM mortars and GPS locators.
The sources also said that the aim of the Pathankot attack and the one in Afghanistan was to derail the Indo-Pak talks.