Justin Trudeau says Russia must be held at least partly accountable for the chemical attack in Syria because of its support for the Assad government.
The prime minister made the comments as he visited the scene of one of Canada's most iconic moments during the Second World War, Juno Beach.
He says countries that have been "supportive" of Bashar Assad bear some responsibility for last week's gruesome chemical attack on civilians, which killed more than 80 people.
He also says the way towards peace and stability in the country does not include the infamous Syrian president.
Trudeau says he has spoken with the leaders of the U.S., Germany, France and Britain, and they agree international community must display ``unity, solidarity and firmness'' to end the conflict in Syria.
The prime minister called on the international community not to repeat the "terrible mistakes" of the past.