– The sidelines of summits are full of talks between leaders, their ministers and aides, but the huddle between Barack Obama and Vladimir Putin at the Group of 20 in Turkey Sunday was heavy with significance.

The meeting on Syria lasting more than 30 minutes was the first since the Russian president surprised his U.S. counterpart in September by returning from talks in New York and sending in his warplanes to prop up Syrian leader Bashar Assad. Since then, terrorism has taken over the global agenda and provided common ­purpose, with militants linked to ISIL bombing Beirut, blamed for downing a Russian passenger jet and killing more than 129 people in Paris on Friday.

“We have all seen the horror that took place recently in Paris and we sympathize with the affected people,” Putin said in the Turkish coastal resort of Antalya before he met with Obama. “We are always in favor of joining efforts to deal effectively with the terrorist threat. Of course it is necessary to act in strict accordance with the United Nations charter.”

After leaving last year’s G-20 summit in Brisbane, Australia, early following a berating from world leaders over stoking conflict in Ukraine, Putin arrived in Turkey with a narrative of collaboration over his vision for ending the Syrian war and tackling terrorism.

His deputy foreign minister overseeing U.S. relations talked earlier on Sunday of how the atrocity in Paris can shift priorities in Washington, while another Russian official said ties with the West already have strengthened in recent days.

Obama welcomed efforts by all nations to confront the Islamic State in Iraq and the Levant and noted the importance of Russia’s military efforts in Syria focusing on ISIL, a White House official said after the meeting. Both leaders endorsed a plan for a political transition in Syria forged by diplomats in Vienna Saturday who were galvanized by the Paris attacks.

Both the United States and Russia are increasing their military activity in Syria, raising concerns the war may morph into a proxy fight between the two powers. Putin’s intervention shifted the balance of power, forcing the Obama administration to reassess its strategy of supporting Syrian opposition fighters who are battling ISIL and Assad’s military.

In their talks, Obama and Putin agreed on the need for a Syrian-led and Syrian-owned political transition, which would be proceeded by U.N.-mediated negotiations between the Syrian opposition and regime as well a cease fire, according to the White House official.