has the USA turned to a menace?

It´s about the well-known sense of antiamericanism growing up all around the world.
I live in Brazil, a country which has always been sympathetic and receptive to the American culture.
Despite of it, we here can also see that increasing feeling of antiamericanism, which has increased specially because of the policy of preventive war adopted by President Bush.
It makes us to hear things as that USA is not a friendly country, but a real menace, in so far as it would not hesitate in striking another country, in case of a minimal conflict of interests.
I think it´s absurd. As a great admirer of American people and culture, and specially of its values, I still believe the USA is not a menace, but a friendly and welcoming country.
...Am i right?