Addressing the UN General Assembly on Wednesday, US President Barack Obama called on member nations to join the United States in its fight against different forces that posed a threat to the world order.

The rise of jihadist group "Islamic State" (IS), in particular, was a challenge that the entire international community must address, he said.

"This is not simply a matter of words. Collectively, we must take concrete steps to address the danger most by religiously-motivated fanatics," Obama said.

The US began conducting airstrikes in recent weeks against the terrorist network strongholds in Iraq. It expanded its operations against IS earlier this week, making air strikes within Syria territory, where the jihadist group also controls swathes of land.

Obama's authorization of military action in the name of counter-terrorism has raised concerns in the US, where memories of failed occupations in Afghanistan and Iraq over more than a decade remain fresh in the minds of a war-weary American public.

The US president told the assembly that his country had an obligation to the world to intervene as "heir to a proud legacy of freedom," but added that Washington would limit its campaign.

Muslim world must battle extremism

The seemingly sudden emergency of IS terrorism in Iraq and Syria in recent months coincides with other crises across the region. Not only has the civil war in neighboring Syria unleashed a humanitarian crisis with no end in sight, but terrorist activities have gripped other Middle East nations, including Lebanon, Egypt and Yemen.

"It is time for the world, especially the Muslim communities to explicitly, forcefully and consistently reject the ideology of organizations like al Qaeda and ISIL," Obama said, referring to IS but one of its other names.

To do so, the international community must help break the cycle of sectarian conflicts by supporting investment in civil society, he said, adding that Middle East nations must act themselves.

"No external power can bring about a transformation of hearts and minds. But America will be a constructive and respectful power," he added.

America 'chooses hope'

In contrast to recent press conferences on world crises, President Obama struck a hopeful tone on Wednesday during his General Assembly speech.

America rejected "fatalism or cynism," he said, despite the overwhelming threats to world order posed by Russia in eastern Europe, extremism across several continents and Ebola epidemic in West Africa and the failure of the Israeli and Palestinian goverments to agree on a two-state solution.

"The test of this moment…[is] whether we can solve these problems together."

kms/ipj (AP, AFP, Reuters)