ANTALYA, Turkey — World leaders vowed a vigorous response to the Islamic State group's terror spree in Paris as they opened a two-day meeting in Turkey on Sunday, with President Barack Obama calling the violence an "attack on the civilized world" and Russian President Vladimir Putin urging "global efforts" to confront the threat.
But beyond the tough talk and calls for action, there was little indication of how leaders intended to escalate the assault on the extremist group. The attacks in the heart of Europe — combined with earlier incidents in Lebanon and Turkey, as well as the downing of a Russian airliner in Egypt — suggest the Islamic State is reaching beyond its base in Iraq and Syria, an expansion the West has feared.
"The skies have been darkened by the horrific attacks that took place in Paris just a day and a half ago," Obama said shortly after arriving in Antalya, a seaside resort city just a few hundred miles from the Syrian border. He waved off a question from reporters about whether he would authorize additional action against ISIS.
Turkish President Recep Tayyip Erdogan, the G20 summit host, pledged leaders would produce a "strong message" about fighting international terrorism, though he, too, did not spell out specific steps.
Putin urged nations to pool their efforts to combat terrorism, adding that the fight must respect international law, the U.N. Charter and each nation's sovereign rights and interests.
"We understand very well that it's only possible to deal with the terror threat and help millions of people who lost their homes by combining efforts of the entire global community," Putin said.
As the world leaders came together, not everyone welcomed them with open arms. Police in the Turkish Mediterranean city of Antalya detained dozens of people Sunday during a series of protests denouncing the summit, although the demonstrations were mostly peaceful.
A group of some 500 youths belonging to a Turkish nationalist association gathered in the city, holding up cardboard effigies of Obama and denouncing U.S. interventions in the Middle East. Police allowed the group to march briefly only after they agreed to leave the effigies behind.
Hundreds of members of Turkish left-wing groups and trade unions later held another protest denouncing the summit that gathers the world's wealthiest economies.