Tall

The Stal's trench was large, and it lacked the steps next to the barrier since those aliens were tall enough to peek without needing them.

Khan couldn't remain on the other side of the barrier since he had no cover there, so he jumped inside the trench. The Stal in front and behind him fired their rifles, but he sprinted forward to hide behind the aliens.

Dark blood spurted inside the trench as the bullets hit the aliens, and a loud growl followed the event. The Stal lowered their rifles after that order, and Khan used that chance to slash his knife at the alien that blocked his way. 

The trench was barely enough to contain the Stal. They were too big, and they could prevent Khan from sprinting past them if they stretched their arms. However, he could duck or jump between their limbs while swinging his knife to carve a path.