Maybe it is because the USA is responsible for the deaths of loved ones.
Check out this article for more.
While the US worked on a cease-fire agreement, Israeli warships fired on southern Beirut.link: http://www.csmonitor.com/2006/0810/p01s03-wome.html
By Scott Peterson | Staff writer of The Christian Science Monitor
BEIRUT, LEBANON – With his arm raised and fist clenched, Sheikh Hussein furiously expressed a sentiment rapidly taking hold here.
"We know who our first enemy is: America," he shouted before tearful mourners at a funeral Wednesday for 30 civilians killed by an Israeli airstrike on Monday. The white-turbaned sheikh led the crowd in a militant chant: "Death to America! Death to America!"