The countries and organizations leading talks to secure a cease-fire in Syria reiterated their call on Tuesday for countries to adhere to the fragile cease-fire there, and to work with their allies in the region to comply.

The International Syria Support Group, as the 26-party alliance led by the United States and Russia is known, issued a statement from Vienna, Austria, aimed at enforcing the cease-fire and boosting political negotiations between President Bashar Assad’s regime and rebel groups.