As someone who knows ppl who served in kargil.
I'd say our NLI, Mujahideen indeed had balls of steel. They fuked the shit out of your entire divisions.
NLI (scouts) at time of Kargil was like FC or Rangers in the mountains. The Mujahedeen were similar caliber or lesser in training. In comparison to both these forces structures Pakistan had National Guard units deployed in the rear, the Mujahid force.
NLI as paramilitary force and Mujahid force as NG troops, were trained primarily for defensive operations. The paradigm was constructed as 2 x regular Infantry battalions of Pakistan Army and 1 x Mujahid force Battalion, formed under a Brigade level structure will be deployed in such a way that regular infantry battalions will be used for offensive operations by advancing in enemy territory while Mujahid force battalion will defend against an enemy counter attack or defend an area of low priority.
There was hardly any expectations from NLI. It was formed of scouts, had light infantry weapons and could only conduct policing duties or man observation posts. Just like its not expected that Rangers in Punjab or Sindh are equipped or trained to undertake any offensive action against Indian Army by attacking enemy positions, NLI as paramilitary force was considered the same.
However, when rag tag mujahideen went in the mountains, and then NLI followed, expectations were still low. Pakistan Army wanted to target and bombard main supply roads leading to Siachen with artillery and other weapons, so it needed to get closer to the objective and deploying regular PA infantry initially didn't seem the best idea. Some platoons of SSG were sent in afterwards to support NLI.
Surprisingly, NLI scouts performed better than expected and they kept advancing into IOK where the supply lines became stretched. This was an unexpected result for PA high command as firstly NLI was sought out since the scouts didnt need acclimatization to the weather, more so they were excellent guides in the mountains and also had daunting stamina for advancing on the peaks and hills, where as regular PA forces usually take some time in achieving such metrics when deployed from the plains or the desert during rotation. The NLI advance stopped when it was checked by patrols of Indian Army and then NLI dug in. The supply lines had been stretched too far and the RVFC had an uphill task ahead of them with no motor transport.
From this point onwards, Indian Army regulars were getting thrashed by paramilitary force of Pakistan.
As the conflict went ahead and based on successive advances of NLI, stingers were deployed on the peaks, artillery support was made available, and regular PA infantry battalions were deployed in FEoB.
The
second most important factor was combining irregulars, paramilitary forces and regular forces for
offensive operations inside Indian occupied Kashmir. It came out as;
Mujahideen + paramilitary NLI scouts + mujahid force battalions + regular Pakistan troops (infantry/AD/Arty etc) + SSG.
Like I mentioned that NLI scouts and NG battalions (mujahid force) were trained for defending a zone or an area. They were not trained in combined operations or carrying out attacks against Indian Army. They were trained to dig in and stand their ground against unfavorable odds. In the end, NLI scouts did the same in Kargil war, they dug in and fought till the last man.
Whether this was an accidental discovery or a planned doctrine for the future, Pakistan high command had formed a new offensive tool of war for operations on LOC. Later when the GB scouts were raised a paramilitary forces to fill in for NLI scouts, Pakistan had already changed the doctrine as "offensive-defensive" for wars with India.