There are conflicting reports on whether or not experts from the Organisation for the Prohibition of Chemical Weapons have entered the site of a suspected chemical attack in Syria.
Syrian state media reported they entered Douma on Tuesday along with the country's health minister.
But U.S. State Department spokeswoman Heather Nauert said the delegation had not yet entered Douma.
The OPCW team arrived in Damascus on Saturday and was reportedly blocked access to the suspected attack site by Syrian and Russian authorities.
The Russian military said the team could enter on Wednesday to carry out its probe aimed at seeing which chemicals, if any, were used.
Syria and Russia deny any poison gas attack took place.