Yes it was a surprise so much so that Pakistan which was planning to occupy a few hilly outposts captured a lot of them. The plan was known by just 4 people in Pakistan not even your PM.
Do you know that what the plan was? Pakistan thought Indians won't retaliate much and think it was local Kashmir fighters and that not many weapons would be effective at that altitude. Also if India retaliates on other front and moves forces Kashmir could be taken by Pakistani soldiers.
Bofors and aircraft runs destroyed the outposts. Pakistan couldn't resupply or use the air force or other divisions as it was officially not in India and your air force commander was told of the operation pretty late.
In the end Pakistan lost both domestically and internationally on the Kashmiri problem.
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