XF 1.4 Close forum globally to new posts

We are having a problem currently with new posts being added to our forum. That is all being worked out, but in the mean time we have closed the forum to avoid any further corrupted threads while the solution is being applied.

Just curious... Is there a way to close the forum to new posts globally while leaving it turned on for viewing?

or... is setting permissions for user groups the only way to accomplish this?