The deployment of the drones, which are capable of intelligence gathering and striking targets with Hellfire missiles, will continue through mid-September, Sputnik reported.
European Command said the stationing would allow the forces to conduct air operations and test drones to reassure Latvia and NATO of the United States' commitment to regional security.
The deployment is part of the European Reassurance Initiative, meant to support NATO members and partners against what US officials describe as a rising Russian threat in the region.
Lielvarde Air Base is located southeast of Latvia's capital of Riga and supports operations for Latvian Air force.