Well-done by Scott Shane in The New York Times:
“We must pledge ourselves to support those brave men and women who this very moment are carrying forth the struggle against British imperialism in the streets of Belfast and Derry,” Mr. King told a pro-I.R.A. rally on Long Island, where he was serving as Nassau County comptroller, in 1982. Three years later he declared, “If civilians are killed in an attack on a military installation, it is certainly regrettable, but I will not morally blame the I.R.A. for it.” […]
Of comparisons between the terrorism of the I.R.A. and that of Al Qaeda and its affiliates, Mr. King said: “I understand why people who are misinformed might see a parallel. The fact is, the I.R.A. never attacked the United States. And my loyalty is to the United States.” […]
Mr. Parker was at a birthday party for a friend in London in 1990 when the I.R.A. tossed a bomb onto the roof of the rented hall, a historic barracks. Many people, including Mr. Parker, were injured, but none died, by lucky chance of location and quick medical response, he said.
Clearly, yes, the IRA (like, say, Hamas) focused its violence against a specific national enemy rather than against the United States of America. Equally clearly, if you toss enough bombs at enough birthday parties in London, you’re going to kill Americans sooner or later.