President Obama and five other foreign leaders called Wednesday for an immediate cease-fire in the war-torn Syrian city of Aleppo and a United Nations investigation of alleged war crimes under the regimeof Syrian President Bashar Assad.

“We condemn the actions of the Syrian regime and its foreign backers, especially Russia, for their obstruction of humanitarian aid, and strongly condemn the Syrian regime’s attacks that have devastated civilians and medical facilities …,” Obama and the leaders of Germany, Britain, Italy, France and Canada said in a joint statement.