In 1985, the Irish government boycotted the St. Patrick's Day parade in New York City, the biggest celebration in the Irish American calendar. The cause of its umbrage was Peter T. King, that year's grand marshal and someone the Irish government said was an "avowed" supporter of a terrorist organization, the Irish Republican Army.

King, then a local politician on Long Island, was one of the most zealous American defenders of the militant IRA and its campaign to drive the British out of Northern Ireland. He argued that IRA violence was an inevitable response to British repression and that the organization had to be understood in the context of a centuries-long struggle for independence.

"The British government is a murder machine," King said. He described the IRA, which mastered the car bomb as an instrument of urban terror, as a "legitimate force." And he compared Gerry Adams, the leader of Sinn Fein, the IRA's political wing, to George Washington.

A quarter-century later, King is chairman of the powerful House Homeland Security Committee. After the Sept. 11, 2001, attacks on New York and the Pentagon, he became an uncompromising supporter of the Bush administration's counterterrorism policies. And he has suggested that President Obama "use the word 'terrorism' more often" so people understand the seriousness of his purpose.

As King prepares to hold hearings Thursday on what he called "the extent of the radicalization" of American Muslims, his past as a defender of armed struggle has led critics to assert he is imposing a double standard.

"My problem with him is the hypocrisy," said Tom Parker, a counterterrorism specialist at Amnesty International who was injured by an IRA bomb that struck a birthday party at a military hall in London in 1990. "If you say that terrorist violence is acceptable in one setting because you happen to agree with the cause, then you lose the authority to condemn it in another setting."

"It's ironic that someone who offered such vocal support for the IRA is involved in this kind of witch hunt against Muslims in America," said Ibrahim Hooper, spokesman for the Council on American-Islamic Relations.

But King sees no parallel between the IRA and violent Islamist extremism, which he describes as a foreign enemy or a foreign-directed enemy. His preferred comparison for the IRA is with the African National Congress led by Nelson Mandela; the IRA, no less than the ANC's military wing, was fighting for community rights and freedom, he says.

"I [wanted] a peace agreement, a working agreement, where the nationalist community would feel their rights would be respected," King said in an interview at his Capitol Hill office. "I felt that the IRA, in the context of Irish history, and Sinn Fein were a legitimate force that had to be recognized and you wouldn't have peace without them.

"Listen, I think I'm one of the people who brought about peace in Ireland."

His interpretation of the past draws support from former president Bill Clinton and Tony Blair, who as British prime minister oversaw the most successful phase of the peace process in Northern Ireland. In the 1998 Good Friday Agreement, all parties to the conflict agreed to use "exclusively peaceful and democratic means" to pursue their aspirations.

"He had indeed been controversial (at least with the British!) in some of his earlier statements. But once he saw a path to peace that was just and deliverable, he urged and campaigned for everyone to take it," Blair wrote in an e-mail. "I thought he was right in his concerns about the new global terrorism but could understand why he saw the Irish situation as different."