"During the visit, US and Latvian defence officials signed a five-year Defence Cooperation Strategic Roadmap", Summers said.
The roadmap identifies specific security cooperation priorities that both countries agreed to focus on over the next five years, the readout said. Latvia has become the second Baltic country after Lithuania to sign such an agreement this year.
Shanahan and Pabriks discussed a broad range of defence issues during their meeting, including efforts to improve interoperability and regional command and control measures, the Pentagon said.
NATO has deployed four multinational battlegroups to Estonia, Latvia, Lithuania and Poland as part of a military buildup in response to tensions with Russia that surfaced after a 2014 referendum in which Crimea's residents overwhelmingly voted to rejoin Russia.
Tensions between NATO and Russia have been high due to the alliance's increased military maneuvers in Europe, specifically near Russia's borders. NATO has been explaining its enhanced activities by the need to counteract a security threat allegedly posed by Russia.
Russia has maintained that NATO's fears are unfounded.