German NSA critic denied entry to the US

An anonymous reader writes: Major newspapers in Germany (FAZ, Die Welt, SZ, ...) and the Huffington Post report that the author Ilja Trojanow has been denied to board a plane from Salvador da Bahia to the US where he was invited to attend a conference. He had ESTA documents showing that his visit was approved as part of the Visa Waiver Program and was last year given a visa to teach at the university of Saint Louis. Trojanow was one of the initiators of an open letter urging Chancellor Merkel to take actions against NSA surveillance in Germany.