Pakistan is not putting enough pressure on the Haqqani network and this is the reason that the US Defence Secretary was not giving the necessary certification for release of USD 300 million in coalition support funds to it, a top American general has said.

"As far the strength of the Haqqanis, the Secretary of Defence in August in his response to Congress as a result of the National Defence Act and Authorisation Act of 2015, he was required to respond to Congress on whether there was adequate pressure being placed on the Haqqanis by the Pakistan government," General John Nicholson, Commander of US and NATO forces in Afghanistan said.

"And he said he was unable to certify that there was sufficient pressure being placed on them to justify additional coalition support funds to Pakistan. Kind of a lengthy explanation, but it was his way of saying that there's not, not adequate pressure being put on the Haqqanis," Nicholson told the Pentagon reporters during a news conference here.

"I concur with the Secretary's assessment on that. Then we, that the Haqqanis operationally have been able to conduct operations inside Afghanistan - they constitute the primary threat to Americans, to coalition members, and to Afghans especially in and around Kabul," he said in response to a question.

General Nicholson said US troops in Afghanistan have been authorised by President Barack Obama to take any measures necessary to defend against the Haqqani threat.