And you would be wrong:
1950 Assassination attempt on President Truman. Puerto Rican nationalist kill one District of Columbia policeman during an attempted assassination of President Harry S. Truman outside of Blair House in Washington, D.C.
1954 Shooting in the U.S. House of Representatives. Five members of Congress are wounded by gunfire during an attack by Puerto Rican nationalist on the U.S. House of Representatives.
1972 Fraunces Tavern Bombing. Four people die in this bombing at a historic tavern in downtown New York City. The Puerto Rican nationalist group FALN is blamed for the attack, one of the 49 bombings in New York attributed to them between 1974 and 1977
1975 LaGuardia Airport Bombing. Eleven are killed, 75 are injured in this attack by Croatian nationalists at this New York City Airport.
1976 Letelier Assassination. Orlando Letelier, the former Chilean ambassador to the United States, is killed by a car bomb in Washington, D.C. The bomb, planted by Chile's Pinochet government, also kills one of Letelier's associates while injuring another.
1981 Kennedy Airport Bombing. One man is killed when a bomb planted by a group calling itself the Puerto Rican Armed Resistance goes off in a men's bathroom at New York City's international airport.
1983 U.S. Senate Bombing. A bomb goes off in the cloak room next to U.S. Senate in the Capitol Building. Two left-wing radicals plead guilty to the attack.
1993 World Trade Center Bombing
1995 Oklahoma City Bombing
1996 Olympic Bombing
1997 Abortion Clinic Bombing
We won't even bother to discuss the rash of airplane hijackings from the early 60's on or the looneys of the 1960s and 70s.