Security Council Resolution 2254: para. 12.

12. Calls on the parties to immediately allow humanitarian agencies rapid, safe and unhindered access throughout Syria by most direct routes, allow immediate, humanitarian assistance to reach all people in need, in particular in all besieged and hard-to-reach areas, release any arbitrarily detained persons, particularly women and children, calls on ISSG states to use their influence immediately to these ends, and demands the full implementation of resolutions 2139 (2014), 2165 (2014), 2191 (2014) and any other applicable resolutions;