„My aim is the United States of Europe — modelled on federal states like Switzerland, Germany or the U.S.,“ she told Der Spiegel in 2011. She repeated her call for a federal EU in an interview with Die Zeit in 2016, adding: „I imagine the Europe of my children or grandchildren not as a loose union of states trapped by national interests.“

As defense minister, she pushed for greater security cooperation in the EU, urging a „defense union“ and calling for the establishment of an „army of Europeans.“