Like the few soldiers who got tortured in Vietnam, 9/11 is an incredibly small price to pay in exchange for all the war crimes, destabilization, and brutalization that occurred before and after the attacks.
in contrast the Phoenix Program tortured and assassinated something like 78,000 Vietnamese "suspected" of aiding the PAVN
EDIT: here's NATOpedia's take, my recollection was a little off
Throughout the program, Phoenix "neutralized" 81,740 people suspected of VC membership, of whom 26,369 were killed, and the rest surrendered or were captured
Look at this ProPublica article/documentary called Terror in Little Saigon. It details how south Vietnamese refugees who were officers and generals assassinated journalists and other Vietnamese immigrants in the US who didn’t support their delusional Bay of Pigs style invasion of Vietnam. The FBI knew about this but did nothing about it.