(Associated Press) - Trying to reassure a nation on edge, President Barack Obama said Sunday the Islamic State group "cannot strike a mortal blow" against the U.S., and he warned that overreacting to the Paris attacks would play into extremists' hands. "We will destroy this terrorist organization," he vowed.

Ending a trip to Asia, Obama implored Americans not to let the specter of terror cause them to compromise their values or change the way they live.

"We do not succumb to fear," he said. "The most powerful tool we have to fight ISIL is to say that we're not afraid, to not elevate them, to somehow buy into their fantasy that they're doing something important," Obama said, using an acronym for the terrorist organization.

Since IS militants killed 130 in France nine days ago, Obama's strategy has come under repeated questioning. He dismissed the group's global prowess of IS and said, "They're a bunch of killers with good social media."

Rejecting the notion of an existential threat, Obama said IS "can't beat us on the battlefield, so they try to terrorize us into being afraid."

"I think it is absolutely vital for every country, every leader, to send a signal that the viciousness of a handful of killers does not stop the world from doing vital business," Obama said. The president and world leaders are set to gather in Paris next week for long-scheduled climate talks. The White House has insisted there will be no change in plans.

Obama also said there was an "increasing awareness" by Russian President Vladimir Putin that IS is Moscow's gravest threat in the Middle East. IS claimed responsibility for downing a Russian passenger jet in Egypt last month with 224 on board.

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