"They (ISI) provide financial support (to extremist organisations). It provides technical support. It provides physical support. They (Pak officials) are allowing the safe heavens to operate," a defence official told PTI on condition of anonymity as he is not authorised to speak to the media.
Another defence department official said that Pentagon has been providing such evidences to Pakistan "since ages" but it is only after the recent attack on a hotel in Kabul and the US Embassy in Kabul that this crossed all limits and the Defence Department decided to go public.
But the senior defence official maintained that these evidences gives concrete proof of the relationship between ISI and the extremist organisations including Haqqani network and LeT.
The senior defence official familiar with it refused from giving further details of the type of evidences that the US has provided to Pakistan, based on which Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff, told a key Congressional committee, last week that the Haqqani network "acts as a veritable arm" of Pakistan's ISI.
Officials said Mullen shared his thoughts and text of his remarks with Defence Secretary Leon Panetta, before he went to make such a strong comment against Pakistan in a public hearing before the Senate Armed Services Committee.