BEIRUT (AP) — The Latest on the Syrian conflict (all times local):

A Kurdish Syrian refugee waits for transport during a sand storm on the Turkish-Syrian border near the southeastern town of Suruc in Sanliurfa province, Sept. 24, 2014. Reuters/Murad Sezer U.N.-mandated investigators say they have solid evidence a Russian-built plane used by Syrian President Bashar Assad's air force conducted a sarin-gas attack in the spring that killed at least 83 civilians and sparked a retaliatory U.S. strike.

The latest report by the Commission of Inquiry on Syria also says U.S. forces failed to take "all feasible precautions" to protect civilians in attacking alleged terrorists in Aleppo in March, destroying part of a mosque complex.

The report offers some of the strongest evidence yet of allegations that Assad's forces conducted the April 4 attack on Khan Sheikhoun in rebel-held Idlib province.

The U.S. quickly launched a punitive strike on Shayrat air base, where the report says the Sukhoi-22 plane took off.

The report issued Wednesday covers a span from March to early July.