RIGA, Latvia — The Canada-led NATO brigade in Latvia has moved beyond its original “tripwire” deterrence posture and is now focused on mounting a credible defense of the Baltic country bordering Russia, according to its commander, Col. Kris Reeves.Reeves said the shift towards what he described as “tactical credibility” has meant establishing forward locations and stationing troops near Latvia’s eastern border, in the terrain where they would ac…