WASHINGTON: The United States has suspended $1.66 billion in security assistance to Pakistan , following President Donald Trump 's directive in this regard early this year, the Pentagon has said."$1.66 billion of security assistance to Pakistan is suspended," Col Rob Manning, spokesman of the Department of Defense told reporters in an email response to questions on Tuesday.No further breakdown of the suspended security assistance to Pakistan was provided.According to David Sedney, who served as Deputy Assistant Secretary Defense for Afghanistan, Pakistan and Central Asia during the previous Obama administration, the blocking of military assistance to Pakistan, which began in January of this year is a strong signal of American frustration."But, so far Pakistan has taken no serious steps to address the core US concern - that Pakistan tolerates and often encourages groups which use violence against Pakistan's neighbors," Sedney told PTI."Pakistan's leaders have promised cooperation, but beyond words, serious cooperation has not happened, therefore President Trump is frustrated and so are most Americans," he said in response to a question."This frustration does not ignore the suffering that Pakistani people have undergone. It just asks Pakistan to recognise that it should act to help stop the suffering of others," said the Senior Associate at the Center for Strategic and International Studies think-tank.Previously, Sedney was at the Department of State and the National Security Council, as well as Acting President of American University of Afghanistan.He was a part of the Pentagon when Osama bin Laden was killed in a daring raid by US commandoes in Abbottabad .Over the last few days Trump has said that people in Pakistan knew about the presence of bin Laden."On Osama bin Laden, I agree with the views of Carlotta Gall of the New York Times who reported in her book, 'The Wrong Enemy' that a very small group of very senior Pakistani military leaders knew about Osama Bin Laden's presence in Pakistan. I have not seen any evidence that his presence in Abbottabad was widely known by many in Pakistan," Sydney told PTI in an interview.While Pakistan has suffered terribly from terrorism by Islamic extremists, Islamabad has also enabled extremists groups that attack its neighbours, he observed.After years of dithering, in recent years Pakistan's security forces have moved strongly against the extremists that threaten the Pakistani state, he added."What the US seeks, what President Trump is asking for, is for Pakistan to take the same kind of measures against the Taliban , against Lashkhar-e-Taiba, and against all groups in Pakistan that threaten Pakistan's neighbors," he said."But, we still see the Taliban moving weapons, fighters and money through Pakistan. We still see Taliban commanders taking refuge in Pakistan, keeping their families in Pakistan, holding meetings and conducting training in Pakistan, and shipping explosives from Pakistan into Afghanistan," Sydney alleged.We see leaders of sanctioned organisations acting freely in Pakistan and speaking publicly in favour of violence, he said."If Pakistan would take some strong measures against the Taliban, peace would come to Afghanistan quickly," he argued.The US Secretary of State Mike Pompeo has roped in former top American diplomat Zalmay Khalilzad for peace talks with the Taliban.Both Afghanistan and Pakistan would benefit from a huge "peace dividend", he asserted."Similarly, if Pakistan would take strong measures against groups which act against India, Pakistan would harvest huge economic benefits from better economic ties with India," Sedney said.