The impact of LGBTQ (lesbian, gay, bisexual, transgender, and queer) issues on U.S. foreign relations is an understudied area, and only a handful of historians have addressed these issues in articles and books. Encounters with unexpected and condemnable (to European eyes) sexual behaviors and gender comportment arose from the first European forays into North America. As such, subduing heterodox sexual and gender expression has always been part of the colonizing endeavor in the so-called New World, tied in with the mission of civilizing and Christianizing the indigenous peoples that was so central to the forging of the United States and pressing its territorial expansion across the continent. These same impulses accompanied the further U.S. accumulation of territory across the Pacific and the Caribbean in the late 19th century, and they persisted even longer and further afield in its citizens’ missionary endeavors across the globe. During the 20th century, as the state’s foreign policy apparatus grew in size and scope, so too did the notions of homosexuality and transgender identity solidify as widely recognizable identity categories in the United States. Thus, it is during the 20th and 21st centuries, with ever greater intensity as the decades progressed, that one finds important influences of homosexuality and gender diversity on U.S. foreign policy: in immigration policies dating back to the late 19th century, in the Lavender Scare that plagued the State Department during the Truman and Eisenhower presidencies, in more contemporary battles between religious conservatives and queer rights activists that have at times been exported to other countries, and in the increasing intersections of LGBTQ rights issues and the War on Terror that has been waged primarily in the Middle East since September 11, 2001.