Canada leads one of four battalions deployed by the Western defence alliance on its eastern flank in 2017 in a deterrence and defence posture following Russia's annexation of Crimea in 2014.

"We are ready to support our allies while facing global threats to security," said Trudeau, adding that Canada's current mission initially slated to expire in 2019, "will be prolonged for four years."

"Canada will not change its attitude towards security of the Baltic countries," Trudeau told reporters at a press conference with his Latvian counterpart Maris Kucinskis.

The Latvian premier hailed Ottawa's decision to extend its mission as "the perfect gift to Latvia on its centenary".

Later on Tuesday, Trudeau was due to visit some 450 Canadian troops deployed for Operation Reassurance, which is Canada's largest sustained military presence in Europe in more than a decade.

In total, over 1,000 NATO troops from nine other alliance members are deployed in the Latvian battalion.

The other three NATO battalions are based in Estonia, Lithuania and Poland and are led by Britain, Germany and the United States, respectively.

Trudeau's visit is the first ever by a Canadian head of government to Latvia, his office said. He now heads to Brussels for the NATO summit on July 11 and 12.