Yes and they have many other links in the army. It's not just HTs. Many Islamist and their followers are pro Iran, pro Saudia, pro UAE, pro Qatar, pro Turkey. Pakistan army tolerates them as they face pressure from those countries who fund them but those Islamist who want to become independent are treated as extremist and terrorists.
Over the decade I learnt that you can only counter a powerful thought with another powerful thought. Hts and Islamist claim they are working for ummah welfare and want United Muslim Nations in order to protect the Muslims from western onslaught(very powerful idea)
The problem is Saudia, UAE, Qatar, Turkey, Iran, Egypt all want to lead the ummah and everybody has their own islamists. Then some islamists are controlled by RAW, CIA and Mossad.
Regarding HTs, it's a mystery who funds them, the closest I have come to is either Mi5/mi6 or Qatar and only their senior leaders are sellouts. Other leaders and followers live in fairy land and have no idea what is happening. They believe when Khilafah comes they will be relaxing on a beach with a powerful military protecting them.
However I do believe HTs can become a great asset if you can get their loyalty. They only want power. It can come from anybody.