[mmichaels1970]

The Russian embassy like American Embassies in other countries is sovereign territory of Russia or the USA., so technically the child is not born in the USA.

Which is why I said "they drove to a hospital". Thus, they were on American soil when Boris was born.

[srmanuel]

Two sources of information that should clarify the issue.

https://www.uscis.gov/green-card/green-card-eligibility/green-card-for-a-person-born-in-the-united-states-to-a-foreign-diplomat

Are babies born in the USA automatically citizens?
Amendment XIV, Section 1, Clause 1 of the U.S. Constitution directs that all persons born in the United States are U.S. citizens. This is the case regardless of the tax or immigration status of a person’s parents