...for Peter King, chairman of the US Congressional Committee on Homeland Security, who has used his position to launch an investigation into what he calls “the radicalisation of Muslims in the United States”. His move has revived memories of Senator Joseph McCarthy's committee on “Un-American activities” in the 1950s which deteriorated into a witch hunt against alleged Communists and “fellow-travellers” working in the government and media. A senior administration security adviser said that “guilt by association” should not be practised in the US.