8 USC 1401 (g) is the statutory definition (it could be challenged, but good luck, it is solidly rooted in common law and original intent). Thomas’s father had only been a US Citizen for two years at the time of his birth. He would have to have been in the US (or in the US Military) as a citizen for 5 years.
“Petitioner Jermaine Amani Thomas was born on August 9, 1986, in a military hospital located on a U.S. military base in Frankfurt, Germany. Thomasâs father, a United States citizen, was a member of the United States military serving on the base. Thomasâs father first entered the United States in September 1977, enlisted in the United States Army in 1979, and became a United States citizen in May 1984. Thomasâs mother was a citizen of Kenya. Thomas was admitted to the United States as a lawful permanent resident in July 1989. His visa form listed his nationality as Jamaican. “