Harper admits that lack of international action in light of the apparent use of chemical weapons would set an "extremely dangerous precedent," but adds his government is reluctant to the idea of western military action.
Harper says the conflict in Syria is "overwhelmingly sectarian in nature" and doesn't appear to have any "ideal or obvious outcomes" for a solution at present.
Syrian President Bashar Assad says his country will defend itself against any foreign aggression.
Meanwhile, U.S. President Barack Obama declared Wednesday that the Syrian government was responsible for a chemical weapons attack on its own people, laying the groundwork for an expected U.S. military strike.
But British Prime Minister David Cameron is promising to hold off on any action until a UN inspection team on the ground can complete its investigation.
The UN says the team should wrap up its inspection Friday and report its findings Saturday.
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