NEW YORK — Secretary of State John Kerry says the week-old truce in Syria brokered by the U.S. and Russia is “holding but fragile” despite persistent violence and a lack of aid deliveries to besieged communities.

Speaking Monday on the sidelines of the U.N. General Assembly, Kerry said some humanitarian assistance is moving but it’s too soon to say if it will meet the requirements of the cease-fire deal. The truce took effect last Monday with the goal of creating a joint U.S.-Russia military facility to coordinate airstrikes on the Islamic State group and al-Qaida affiliates. That was to be set up after seven days of reduced violence and sustained aid deliveries to Aleppo and other areas.

Although Kerry professed hope, U.S. officials said Monday conditions were still not right to set up the Joint Implementation Center.