Nonetheless, he stressed that his new Ostpolitik did not neglect the close ties of the Federal Republic with Western Europe and the United States or its membership in NATO. Indeed, by the late 1960s, the unwavering stance of the Hallstein Doctrine was actually considered[by whom?] detrimental to US interests; numerous American advisors and policymakers, most notably Henry Kissinger, urged Bonn to be more flexible.