Flowers and the shoe of a victim rest outside of the Bataclan concert hall in Paris in a memorial to victims of the Nov. 13, 2015, terrorist attack there. Pascal Le Segretain/Getty Images

U.S. President Barack Obama and French President François Hollande paid a visit Sunday night to the Bataclan, the concert hall where gunmen shot into a crowd of hundreds of people Nov. 13. The Bataclan was the scene of the deadliest attack during the coordinated onslaught across Paris.

Obama, who had just arrived in Paris for the world climate summit, placed a flower at the makeshift memorial and then stood silently, his head bowed and his hands clasped in front of him, Reuters reported. Afterward he walked away with his arms around Hollande and Paris Mayor Anne Hidalgo, who was also present.

Following the Paris attacks, Obama said the United States would do all in its power to support France in its fight against the Islamic State group, also known as ISIS. The men that carried out the attack at the Bataclan were members of the Sunni Muslim extremist group, which claimed responsibility.

France and the U.S. have increased the number of airstrikes on ISIS forces in Iraq and Syria since the Paris attacks, targeting convoys, weapon warehouses and militants.

Obama visited the Bataclan ahead of the United Nations climate change summit, which was pushed back in the wake of the Paris attacks. More than 150 world leaders are expected to attend the summit in Paris, which is supposed to lay out a landmark global deal on limiting greenhouse gas emissions.

Before the summit opening, hundreds of people protested Sunday, calling on world leaders to implement realistic and effective policies that can stop global warming. In Paris, more than 200 demonstrators were arrested after clashes. Hundreds of thousands of people have marched worldwide to demand climate action.