Bono has announced the 10th anniversary of the September 11 terror attacks makes him feel like a "very proud American".
The Irish singer said: "It's just too big a moment in all our lives. Even if you're not American, everyone became an American that day."
The U2 frontman will be in New York on Sunday with his wife Ali Hewson for a fashion event promoting a men's collection for their EDUN line.
The couple launched the not-for-profit fashion company in 2005 to raise awareness for business opportunities in Africa.
Bono was speaking from the red carpet of the screening of U2 documentary From The Sky Down, which opened the Toronoto International Film Festival.
The film chronicles the band's recording of their seminal 1991 album Achtung Baby.
But Bono revealed he struggled to watch it as he hates listening to U2's hits.
He said: "I saw a rough cut. I found it very hard to watch to be honest with you. We're not very good at looking back at things.
"I mean Edge, when he put together our Best Of collections, forced me, actually had to physically force me to listen to it before it went out, because I'm just not interested in what we've done, I'm always more interested in what we're about to do.
"But you know, for this album, we made an exception."