How do i choke someone?

When im dragging a soldier how can i let my hiding characters deliver the soldier to the truck?

Sneak up behind the soldier you wish to grab, press and hold square. L interrogates while repeatedly tapping [] chokes him out. And before you ask, you cannot lethally kill someone by slicing their throat or choking them.
Drag the body to the box, then i believe Roy will call you and tell you about other teammates capturing, etc.

Thanks

Np.