Originally Posted by FWAAA

In the wake of September 11, 2001, frequent checkpoint security "failures" resulted in the evacuation and rescreening of multiple LAX terminals even though the "failure" was at T-4 or T-5 or T-6, etc. The fear-mongers said that because of the tunnels, all connected terminals had to be re-screened.

I don't recall who, exactly, gave the order to close the tunnels but IIRC, all of the south side tunnels were locked in late 2001. In the years since, however, all of the tunnels were re-opened except for the T-4 to T-5 tunnel. With AS now in T-6, I'd vote to re-open the T-4 tunnel.