.gov top-level domain

The .gov top-level domain is a domain extension reserved to U.S. government agencies (except U.S. military - see .mil). This top-level domain was registered on January 1, 1985, and it is managed by the Cybersecurity and Infrastructure Security Agency (CISA). Note that foreign governments may not use .gov. These governments may use traditional domain names (like gouv.fr in France, gov.scot in Scotland), but do not have dedicated top-level domains.
Exemple domain using .gov: fbi.gov.

.mil

WHOIS
Delegation records for .GOV (iana)
cisa.gov