These sanctions, according to Daniel T. Griswold, failed to change the behavior of sanctioned countries; but they have barred American companies from economic opportunities, and harmed the poorest people in the countries under sanctions.[55] Secondary sanctions,[lower-alpha 1] according to Rawi Abdelal, often separate the United States and Europe because they reflect US interference in the affairs and interests of the European Union.[56] Since Trump became the president of the United States, Abdelal believes, sanctions have been seen not only as an expression of Washington's preferences and whims, but also as a tool for US economic warfare that has angered historical allies such as the European Union.[57]