US President Barack Obama has cited the deadly Sydney siege in a speech to world leaders and officials at a Washington DC summit aimed at countering violent extremism.
Obama listed four areas on Thursday where he believed governments around the world could focus on.
The president said governments must be unwavering in their fight against terror organisations; confront the "warped ideologies" espoused by terrorists; address the economic grievances terrorists exploit; and address the political grievances terrorists exploit.
"As we speak, ISIL is terrorising the people of Syria and Iraq and engaging in unspeakable cruelty - the wanton murder of children, the enslavement and rape of women, threatening religious minorities with genocide, beheading hostages," Obama said.
"ISIL-linked terrorists murdered Egyptians in the Sinai Peninsula and their slaughter of Egyptian Christians in Libya has shocked the world.
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"Beyond the region, we've seen deadly attacks in Ottawa, Sydney, Paris, and now Copenhagen."
Australian attorney-general George Brandis is representing Australia at the summit.
