Former prime minister Jean Chrétien says he supports Liberal Leader Justin Trudeau's decision to oppose Canada's air combat mission in Iraq.

In a column for the Globe and Mail Friday, Chrétien calls the deployment of fighter planes a "very marginal" response to the crisis caused by Islamic State militants.

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In an opinion piece published Friday, Jean Chrétien writes that he believes the best contribution Canada can make to the U.S.-led ISIS mission is by engaging in 'massive, not token, humanitarian assistance.' (Nathan Denette/Canadian Press)

Chrétien writes that he believes the "best contribution Canada can make is by engaging in massive, not token, humanitarian assistance."

He says that is why he supports the position taken by Trudeau.

Chrétien also recalled how in 2003, there was no louder critic than then-Opposition Leader Stephen Harper to his decision to keep Canada out of the Iraq war.

'Disastrous results'

A wrong decision, such as that invasion, wrote Chrétien, "can have disastrous results that reverberate for years."

He said the legacy of colonialism in the Middle East was exacerbated by the Western military intervention in Iraq in 2003 and that the current rise of ISIL "is in large part a result of that war."

Unfortunately, wrote Chrétien, "Harper did not understand that history in 2003, and he does not understand it today."

The former PM added that while the "Islamic State's atrocities must be stopped ... Western countries must be cognizant of the region's history in deciding how to act."

Chrétien said Canada should offer to immediately take 50,000 refugees fleeing the Islamic State and allocate $100 million for the World Food Program to help feed refugees facing a harsh winter.