U.S. Secretary of State John Kerry says more than 50 countries have joined the coalition to fight the Islamic State extremist group.

Flanked by Iraq's president and foreign minister, Kerry was speaking hours after a U.S.-led coalition conducted airstrikes against the militants in Syria.

He says the fight must be led by countries in the region.

He says the United States has made clear that "we will not allow geography or borders to prevent us from taking action" against the Islamic State militants.

"We will hold them responsible for their grotesque atrocities," Kerry says. "And we will not allow them to find safe haven where they think they can have sanctuary against accountability."

If left unchecked, Kerry warned that the group would be a threat to countries, "including here."