In an interview with Dawn.Com, retired Major General Athar Abbas said that country suffered a lot due to reluctance of his former boss who was urged by his officers to launch operation in 2010.
"The final decision, of course, was always that of the chief, but formation commanders recommended (in 2010-11) that unless we launched an offensive in the area (North Waziristan) and cleared it, we wouldn't be able to control the spread of militancy and terrorism," he said.
He was also worried due to lack of political support and feared that religious parties would create a problem.
"He (Kayani) was concerned about the reaction of the religious right... For six years, he kept vacillating over the issue," said Abbad.
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In comparison he said that current military chief General Raheel Sharif decided in six months "that this is the crux of the problem".
"He (Sharif) took a decision. It's a matter of how decisive you are, how much you have the ability to sift essentials from non-essentials," he said.
"Not everything happened because of North Waziristan, but it was the main source. Over 5,000 soldiers were killed and 10,000 more lost limbs. There are the economic losses and the huge loss to Pakistan's international image."
When asked if he would support action against Kayani for the "costly indecision", the former spokesman said, "I think history will judge it".
Abbas was spokesman when Pakistan launched two successful operations in Swat and South Waziristan in 2009.
Abbas first criticised Kaynai in an interview with BBC and termed his reluctance as main reason for delay in North Waziristan operation.