Syria’s government stepped up attacks across the country Sunday, June 17, trapping thousands of Syrians in besieged towns, a day after United Nations monitors stopped their work there due to a surge in violence, The Wall Street Journal reported. The attacks raised fears that the suspension of the U.N. mission would lead to even greater violence and chaos, as the only peace plan for Syria unraveled. Syrian opposition leaders called for urgent action from the U.N. Security Council, where Western nations calling for President Bashar Assad’s ouster and his main international ally, Russia, have been deadlocked amid the escalating Syrian conflict. On Sunday, the violence appeared to focus on the city of Homs—long an epicenter of the uprising—and a suburb of the capital Damascus. At least 45 people were killed, according to opposition activists.