Speaking alongside Latvia's ambassador to NATO, Maris Riekstins, Lute said he was intown to check on the US' "persistent presence" in the region, designed to reassure its allies worried by the actions of Russia in Ukraine.
"This is a direct result of the newly aggressive actions by Mr Putin, first in Crimea and now in Donbass," Lute said, adding that Putin had "thrown out the rulebook" that had created stability in Eastern Europe sine the fall of the Soviet Union.
"This has caused concern on NATO's eastern flank," Lute said.
"There's a concern that our easternmost allies, including Latvia, understand that article 5 of the NATO Treaty means exactly what it says, which is that an attack on one is considered by the others as an attack on all."
US troops would remain in Latvia indefinitely, for "as long as it takes" Lute reassured.
"Their presence demonstrates that Article 5 means what it says" he said and that it would "demonstarte to any country that might have aggressive notions in this area that the alliance stands 28 [members] for 28."
