Voicing its determination to ensure elimination of terror threat emanating from Pakistan, the U.S. on Thursday said the steps taken by Islamabad so far were not sufficient in this direction and there is a "long way to go". U.S. Assistant Secretary of State Richard Boucher, who held talks with Foreign Secretary Shivshankar Menon soon after his arrival from Islamabad, stressed the need for tracking down individuals and organisations behind the Mumbai attacks by following leads "as far as they go". The U.S. official, who has told the Pakistani leadership to take the probe into Mumbai attacks to its logical conclusion, briefed Menon on his discussions in Islamabad. "The principal topic is the Mumbai attacks. It was a horrible attack against Indians, Americans and others. We will continue to follow up on that," Boucher told reporters after meeting the Foreign Secretary. He said the U.S. and India are both "determined to find out who did this, how it was done and how to make sure it does not happen again." He said the U.S. would keep making efforts to ensure that "this threat to Indians, Americans, whole world, including Pakistan, is eliminated. "I think what we have seen so far is what we have said-- it is a promising start. In Pakistan we have seen some people detained, we have seen offices go down, they (Pakistan Government) are back against the Jaamat-ud Dawah," he said. However, "We obviously do not think steps so far have eliminated the threat," Boucher said, adding "The goal that we all have is to make sure that this cannot happen again."