US has asked Pakistan to make more efforts to root out violent extremism. Terming the assassinated Pakistan's Punjab governor Salmana Taseer, an individual who had worked hard to promote tolerance, White House Press Secretary Robert Gibbs said that Washington is committed to the efforts that the Pakistani government is and must undertake to root out extremism and to bring greater peace and stability to that country and to the region.Gibbs was responding to questions about the assassination, which is said to be a reflection of violent extremism in the country.Taseer was gunned down by his own security guard who claimed he was offended by the Governor's criticism of the controversial blasphemy law.