"This is not just (a) government to government thing. Headley's lawyers are involved in it, so we have to have his agreement," Blake said when he was told that India was yet to get access to 49-year-old Headley, the Pakistani-American Lashkar-e-Taiba (LeT).
The US is attending the SAARC summit as an observer.
Asked if India should indulge in the kind of action, against LeT, as was done with the Taliban in Swat valley and Waziristan, Blake said the US felt the same.
"This is high priority for US and it should be a priority for US as these groups not only threaten India but the US and other countries and have potential to threaten Pakistan too."
"So I think Pakistan has an interest in abiding by its own pledge that it will not allow its territory to be used by any terrorist organisation," he said.
Blake said though he was happy by the progress made in Swat valley and South Waziristan against the Taliban, whose key leaders have been arrested, he thought progress should include action against groups such as LeT and Jaish-e-Mohammed.