That was how I answered the beginnings of the phone call. In this case, yes, it's literal: there's a volcano threatening to go off at Mount Redoubt in Alaska which could possibly once again (as it did a couple of decades ago) affect the Drift River Oil Terminal, a set of storage tanks that usually stores hundreds of thousands of barrels of crude oil. Chevron refuses to release information about how much oil they have left at the facility, citing Homeland Security concerns. There's a good article on it here.
How is this possibly homeland security information? Everyone already knows where the facility is, has pictures of it, and knows how much oil it generally holds. What Chevron doesn't want to release is information about how much oil it holds right now, now that they've pumped some of the oil out in response to the volcano building up nearby. Of course they have all sorts of economic motives to leave as much oil as possible there and risk it, and people concerned about the environment have opposite motives to push them to get the oil out of the river's floodplain. I don't understand how they even can claim a concern about terrorism without everyone laughing at them.
This is not the first time that terrorism has been claimed as a concern in order to avoid the release of chemical accident information. On the contrary, that started even before 9/11 -- even as industry managed to have its politicians avoid making any requirements that they actually do anything to reduce accident risk. I've worked with this kind of thing for a long time, which is why I got the call in the first place. This may be a good test of Obama's new FOIA policy. It really comes down to one of two alternatives. If the government knows what Chevron is doing to prepare for this volcano, then that information should be FOIA-able. And if it doesn't know, why not?